diff --git a/app/controllers/concerns/cache_concern.rb b/app/controllers/concerns/cache_concern.rb
index 2dfe5e263..62f763fe2 100644
--- a/app/controllers/concerns/cache_concern.rb
+++ b/app/controllers/concerns/cache_concern.rb
@@ -3,150 +3,6 @@
 module CacheConcern
   extend ActiveSupport::Concern
 
-  module ActiveRecordCoder
-    EMPTY_HASH = {}.freeze
-
-    class << self
-      def dump(record)
-        instances = InstanceTracker.new
-        serialized_associations = serialize_associations(record, instances)
-        serialized_records = instances.map { |r| serialize_record(r) }
-        [serialized_associations, *serialized_records]
-      end
-
-      def load(payload)
-        instances = InstanceTracker.new
-        serialized_associations, *serialized_records = payload
-        serialized_records.each { |attrs| instances.push(deserialize_record(*attrs)) }
-        deserialize_associations(serialized_associations, instances)
-      end
-
-      private
-
-      # Records without associations, or which have already been visited before,
-      # are serialized by their id alone.
-      #
-      # Records with associations are serialized as a two-element array including
-      # their id and the record's association cache.
-      #
-      def serialize_associations(record, instances)
-        return unless record
-
-        if (id = instances.lookup(record))
-          payload = id
-        else
-          payload = instances.push(record)
-
-          cached_associations = record.class.reflect_on_all_associations.select do |reflection|
-            record.association_cached?(reflection.name)
-          end
-
-          unless cached_associations.empty?
-            serialized_associations = cached_associations.map do |reflection|
-              association = record.association(reflection.name)
-
-              serialized_target = if reflection.collection?
-                                    association.target.map { |target_record| serialize_associations(target_record, instances) }
-                                  else
-                                    serialize_associations(association.target, instances)
-                                  end
-
-              [reflection.name, serialized_target]
-            end
-
-            payload = [payload, serialized_associations]
-          end
-        end
-
-        payload
-      end
-
-      def deserialize_associations(payload, instances)
-        return unless payload
-
-        id, associations = payload
-        record = instances.fetch(id)
-
-        associations&.each do |name, serialized_target|
-          begin
-            association = record.association(name)
-          rescue ActiveRecord::AssociationNotFoundError
-            raise AssociationMissingError, "undefined association: #{name}"
-          end
-
-          target = if association.reflection.collection?
-                     serialized_target.map! { |serialized_record| deserialize_associations(serialized_record, instances) }
-                   else
-                     deserialize_associations(serialized_target, instances)
-                   end
-
-          association.target = target
-        end
-
-        record
-      end
-
-      def serialize_record(record)
-        arguments = [record.class.name, attributes_for_database(record)]
-        arguments << true if record.new_record?
-        arguments
-      end
-
-      def attributes_for_database(record)
-        attributes = record.attributes_for_database
-        attributes.transform_values! { |attr| attr.is_a?(::ActiveModel::Type::Binary::Data) ? attr.to_s : attr }
-        attributes
-      end
-
-      def deserialize_record(class_name, attributes_from_database, new_record = false) # rubocop:disable Style/OptionalBooleanParameter
-        begin
-          klass = Object.const_get(class_name)
-        rescue NameError
-          raise ClassMissingError, "undefined class: #{class_name}"
-        end
-
-        # Ideally we'd like to call `klass.instantiate`, however it doesn't allow to pass
-        # wether the record was persisted or not.
-        attributes = klass.attributes_builder.build_from_database(attributes_from_database, EMPTY_HASH)
-        klass.allocate.init_with_attributes(attributes, new_record)
-      end
-    end
-
-    class Error < StandardError
-    end
-
-    class ClassMissingError < Error
-    end
-
-    class AssociationMissingError < Error
-    end
-
-    class InstanceTracker
-      def initialize
-        @instances = []
-        @ids = {}.compare_by_identity
-      end
-
-      def map(&block)
-        @instances.map(&block)
-      end
-
-      def fetch(...)
-        @instances.fetch(...)
-      end
-
-      def push(instance)
-        id = @ids[instance] = @instances.size
-        @instances << instance
-        id
-      end
-
-      def lookup(instance)
-        @ids[instance]
-      end
-    end
-  end
-
   class_methods do
     def vary_by(value, **kwargs)
       before_action(**kwargs) do |controller|
@@ -196,11 +52,7 @@ module CacheConcern
     raw = raw.cache_ids.to_a if raw.is_a?(ActiveRecord::Relation)
     return [] if raw.empty?
 
-    cached_keys_with_value = begin
-      Rails.cache.read_multi(*raw).transform_keys(&:id).transform_values { |r| ActiveRecordCoder.load(r) }
-    rescue ActiveRecordCoder::Error
-      {} # The serialization format may have changed, let's pretend it's a cache miss.
-    end
+    cached_keys_with_value = Rails.cache.read_multi(*raw).transform_keys(&:id)
 
     uncached_ids = raw.map(&:id) - cached_keys_with_value.keys
 
@@ -208,10 +60,7 @@ module CacheConcern
 
     unless uncached_ids.empty?
       uncached = klass.where(id: uncached_ids).with_includes.index_by(&:id)
-
-      uncached.each_value do |item|
-        Rails.cache.write(item, ActiveRecordCoder.dump(item))
-      end
+      Rails.cache.write_multi(uncached.values.to_h { |i| [i, i] })
     end
 
     raw.filter_map { |item| cached_keys_with_value[item.id] || uncached[item.id] }
diff --git a/app/models/custom_filter.rb b/app/models/custom_filter.rb
index 0ee9e3532..371267fc2 100644
--- a/app/models/custom_filter.rb
+++ b/app/models/custom_filter.rb
@@ -17,23 +17,8 @@
 class CustomFilter < ApplicationRecord
   self.ignored_columns += %w(whole_word irreversible)
 
-  # NOTE: We previously used `alias_attribute` but this does not play nicely
-  # with cache
-  def title
-    phrase
-  end
-
-  def title=(value)
-    self.phrase = value
-  end
-
-  def filter_action
-    action
-  end
-
-  def filter_action=(value)
-    self.action = value
-  end
+  alias_attribute :title, :phrase
+  alias_attribute :filter_action, :action
 
   VALID_CONTEXTS = %w(
     home
diff --git a/app/models/custom_filter_keyword.rb b/app/models/custom_filter_keyword.rb
index 1812a4308..3158b3b79 100644
--- a/app/models/custom_filter_keyword.rb
+++ b/app/models/custom_filter_keyword.rb
@@ -17,15 +17,7 @@ class CustomFilterKeyword < ApplicationRecord
 
   validates :keyword, presence: true
 
-  # NOTE: We previously used `alias_attribute` but this does not play nicely
-  # with cache
-  def phrase
-    keyword
-  end
-
-  def phrase=(value)
-    self.keyword = value
-  end
+  alias_attribute :phrase, :keyword
 
   before_save :prepare_cache_invalidation!
   before_destroy :prepare_cache_invalidation!
diff --git a/config/application.rb b/config/application.rb
index 990a89383..bab1b46cb 100644
--- a/config/application.rb
+++ b/config/application.rb
@@ -63,6 +63,8 @@ module Mastodon
     # Initialize configuration defaults for originally generated Rails version.
     config.load_defaults 7.0
 
+    config.active_record.marshalling_format_version = 7.1
+
     # Please, add to the `ignore` list any other `lib` subdirectories that do
     # not contain `.rb` files, or that should not be reloaded or eager loaded.
     # Common ones are `templates`, `generators`, or `middleware`, for example.
diff --git a/lib/mastodon/redis_config.rb b/lib/mastodon/redis_config.rb
index e885712f8..10672a535 100644
--- a/lib/mastodon/redis_config.rb
+++ b/lib/mastodon/redis_config.rb
@@ -34,7 +34,7 @@ REDIS_CACHE_PARAMS = {
   driver: :hiredis,
   url: ENV['CACHE_REDIS_URL'],
   expires_in: 10.minutes,
-  namespace: cache_namespace,
+  namespace: "#{cache_namespace}:7.1",
   connect_timeout: 5,
   pool: {
     size: Sidekiq.server? ? Sidekiq[:concurrency] : Integer(ENV['MAX_THREADS'] || 5),