diff --git a/activerecord/lib/active_record/associations/association_scope.rb b/activerecord/lib/active_record/associations/association_scope.rb
index 0e849c06efccd6babc6bd4c63f070a366b8a422d..4220a1499a8269d82204950f26e66c36b96af9d2 100644
--- a/activerecord/lib/active_record/associations/association_scope.rb
+++ b/activerecord/lib/active_record/associations/association_scope.rb
@@ -24,10 +24,10 @@ def scope(association)
         scope = klass.unscoped
         owner = association.owner
         alias_tracker = AliasTracker.create(klass.connection, klass.table_name)
-        chain_head, chain_tail = get_chain(reflection, association, alias_tracker)
+        chain = get_chain(reflection, association, alias_tracker)
 
         scope.extending! reflection.extensions
-        add_constraints(scope, owner, chain_head, chain_tail)
+        add_constraints(scope, owner, chain)
       end
 
       def join_type
@@ -98,7 +98,6 @@ def next_chain_scope(scope, table, reflection, foreign_table, next_reflection)
         end
 
         class ReflectionProxy < SimpleDelegator # :nodoc:
-          attr_accessor :next
           attr_reader :alias_name
 
           def initialize(reflection, alias_name)
@@ -111,36 +110,32 @@ def all_includes; nil; end
 
         def get_chain(reflection, association, tracker)
           name = reflection.name
-          runtime_reflection = Reflection::RuntimeReflection.new(reflection, association)
-          previous_reflection = runtime_reflection
+          chain = [Reflection::RuntimeReflection.new(reflection, association)]
           reflection.chain.drop(1).each do |refl|
             alias_name = tracker.aliased_table_for(
               refl.table_name,
               refl.alias_candidate(name),
               refl.klass.type_caster
             )
-            proxy = ReflectionProxy.new(refl, alias_name)
-            previous_reflection.next = proxy
-            previous_reflection = proxy
+            chain << ReflectionProxy.new(refl, alias_name)
           end
-          [runtime_reflection, previous_reflection]
+          chain
         end
 
-        def add_constraints(scope, owner, chain_head, chain_tail)
-          owner_reflection = chain_tail
+        def add_constraints(scope, owner, chain)
+          owner_reflection = chain.last
           table = owner_reflection.alias_name
           scope = last_chain_scope(scope, table, owner_reflection, owner)
 
-          reflection = chain_head
-          while reflection
+          chain.each_cons(2) do |reflection, next_reflection|
             table = reflection.alias_name
-            next_reflection = reflection.next
-
-            unless reflection == chain_tail
-              foreign_table = next_reflection.alias_name
-              scope = next_chain_scope(scope, table, reflection, foreign_table, next_reflection)
-            end
+            foreign_table = next_reflection.alias_name
+            scope = next_chain_scope(scope, table, reflection, foreign_table, next_reflection)
+          end
 
+          chain_head = chain.first
+          chain.reverse_each do |reflection|
+            table = reflection.alias_name
             # Exclude the scope of the association itself, because that
             # was already merged in the #scope method.
             reflection.constraints.each do |scope_chain_item|
@@ -158,8 +153,6 @@ def add_constraints(scope, owner, chain_head, chain_tail)
               scope.where_clause += item.where_clause
               scope.order_values |= item.order_values
             end
-
-            reflection = next_reflection
           end
 
           scope
diff --git a/activerecord/lib/active_record/reflection.rb b/activerecord/lib/active_record/reflection.rb
index 49ddcaecdf1f8a6226bf7e48167bc1dbfbce1d09..a01eb7b24206093b6f648555990bb118632e710e 100644
--- a/activerecord/lib/active_record/reflection.rb
+++ b/activerecord/lib/active_record/reflection.rb
@@ -1077,8 +1077,6 @@ def source_type_info
     end
 
     class RuntimeReflection < PolymorphicReflection # :nodoc:
-      attr_accessor :next
-
       def initialize(reflection, association)
         @reflection = reflection
         @association = association
diff --git a/activerecord/test/cases/associations/has_many_through_associations_test.rb b/activerecord/test/cases/associations/has_many_through_associations_test.rb
index f8ea51225acefa19b17358df9333d02c9884d1c2..521b388ceef720d26d195ebbc7d7db4b79fa3101 100644
--- a/activerecord/test/cases/associations/has_many_through_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_through_associations_test.rb
@@ -1250,6 +1250,10 @@ def test_has_many_through_do_not_cache_association_reader_if_the_though_method_h
     TenantMembership.current_member = nil
   end
 
+  def test_has_many_through_with_unscope_should_affect_to_through_scope
+    assert_equal [comments(:eager_other_comment1)], authors(:mary).unordered_comments
+  end
+
   def test_has_many_through_with_scope_should_respect_table_alias
     family = Family.create!
     users = 3.times.map { User.create! }
diff --git a/activerecord/test/models/author.rb b/activerecord/test/models/author.rb
index 0a52cc539017cbbea101c538cd2030df3128a56e..3371fcbfccccf349d71255f6613efc899496006b 100644
--- a/activerecord/test/models/author.rb
+++ b/activerecord/test/models/author.rb
@@ -40,6 +40,7 @@ def ratings
            class_name: "Post"
 
   has_many :comments_desc, -> { order("comments.id DESC") }, through: :posts, source: :comments
+  has_many :unordered_comments, -> { unscope(:order).distinct }, through: :posts_sorted_by_id_limited, source: :comments
   has_many :funky_comments, through: :posts, source: :comments
   has_many :ordered_uniq_comments, -> { distinct.order("comments.id") }, through: :posts, source: :comments
   has_many :ordered_uniq_comments_desc, -> { distinct.order("comments.id DESC") }, through: :posts, source: :comments