zeitwerk - Rails 7.2 STI: Invalid single-table inheritance type error when uncommenting relations, validations or state machine

I recently upgraded my Rails application from Rails 5.2 to Rails 7.2 and I am facing an issue related to Single Table Inheritance (STI).

Issue: Whenever I uncomment certain parts of my base model (e.g., validations, associations, callbacks), I get the following error:

(main):16:in `': Invalid single-table inheritance type: MyApp::ChildModel is not a subclass of MyApp::BaseModel (ActiveRecord::SubclassNotFound)

However, if I keep those lines commented, everything works fine, and I can successfully query both the base model and its subclasses.

My items table has an STI column type:

create_table "items", force: :cascade do |t|
  t.string "name"
  t.string "state"
  t.integer "category_id"
  t.string "type", default: "MyApp::ChildModel"
  t.timestamps
end

Base Model:

class MyApp::BaseModel < ApplicationRecord
  include MyApp::StiPreloader

  # Constants for STI subclasses
  PARENT_CLASS = 'MyApp::ParentModel'
  CHILD_CLASS  = 'MyApp::ChildModel'

  scope :active, -> { where(state: 'active') }
  scope :parent_items, -> { where(type: PARENT_CLASS) }
  scope :child_items, -> { where(type: CHILD_CLASS) }

  # Uncommenting any of the following lines causes the error:
  # validates :name, presence: true
  # belongs_to :category
  # before_validation :some_callback
end

Child Model:

class MyApp::ChildModel < MyApp::BaseModel
  belongs_to :category

  before_validation :some_logic

  private

  def some_logic
    # Some logic here
  end
end

My STI Preloader:

module MyApp::StiPreloader
  extend ActiveSupport::Concern

  included do
    cattr_accessor :preloaded, instance_accessor: false
  end

  class_methods do
    def descendants
      return super if preloaded

      self.preloaded = true
      preload_sti
      super
    end

    def preload_sti
      return if preloaded

      types_in_db = base_class.unscoped.select(inheritance_column).distinct
                              .pluck(inheritance_column)pact
      puts "Processing STI for: #{self}"
      types_in_db.each do |type|
        begin
          type.constantize
        rescue NameError => e
          Rails.logger.warn "Skipping STI preload for #{type}: #{e.message}"
        end
      end

      self.preloaded = true
    end
  end
end

Observations: If I comment out certain lines in MyApp::BaseModel, STI works fine.

If I uncomment validations, associations, callbacks, or even state_machine I get the ActiveRecord::SubclassNotFound error.

MyApp::StiPreloader is being used to preload STI subclasses.(Everything works with commenting this aswell )

MyApp::BaseModel.last fails, but MyApp::ChildModel.last works fine.

Running Rails.application.eager_load! does not resolve the issue.

Things I Have Tried:

Ensuring app/models/my_app/child_model.rb exists.

Running Rails.application.eager_load! manually.

Calling MyApp::ChildModel.name before querying MyApp::BaseModel.

Changing the STI preload strategy.

Running Rails.cache.clear.