diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 9803f250..b22e9643 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -1,10 +1,8 @@
 name: Tests
 
 on:
-  push:
   pull_request:
-    branches:
-      - main
+  push:
 
 env:
   ACTIONS_RUNNER_FORCED_INTERNAL_NODE_VERSION: node16
@@ -15,12 +13,16 @@ jobs:
   tests:
     name: Run tests (${{ matrix.image }})
 
+    # prevent workflow jobs run twice on push and pull_request event
+    # see https://github.com/orgs/community/discussions/57827
+    if: github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name != github.event.pull_request.base.repo.full_name
+
     strategy:
       fail-fast: false
       matrix:
         include:
           - image: 1.6.6-erlang-21.3.8.24-debian-buster-20210902-slim
-          - image: 1.17.2-erlang-27.0.1-debian-bookworm-20240701-slim
+          - image: 1.19.3-erlang-28.1.1-debian-bullseye-20251103-slim
 
     runs-on: ubuntu-latest
     container:
@@ -28,7 +30,7 @@ jobs:
 
     steps:
     - name: Checkout
-      uses: actions/checkout@v4
+      uses: actions/checkout@v5
 
     - name: Hex and Rebar setup
       run: |
@@ -44,6 +46,7 @@ jobs:
         key: deps-${{ runner.os }}-${{ matrix.image }}-${{ hashFiles('**/mix.lock') }}
         restore-keys: |
           deps-${{ runner.os }}-${{ matrix.image }}
+
     - name: Install dependencies
       run: mix deps.get --only test
 
diff --git a/test/shared/pubsub_test.exs b/test/shared/pubsub_test.exs
index fe1c0091..7697f9e8 100644
--- a/test/shared/pubsub_test.exs
+++ b/test/shared/pubsub_test.exs
@@ -181,7 +181,7 @@ defmodule Phoenix.PubSubTest do
   @tag registry_size: 2
   test "PubSub pool size can be configured separately from the Registry partitions",
        config do
-    assert {:duplicate, 2, _} = :ets.lookup_element(config.pubsub, -2, 2)
+    assert_ets_duplicate_count(config.pubsub, 2)
 
     assert :persistent_term.get(config.adapter_name) ==
       {config.adapter_name, :"#{config.adapter_name}_2", :"#{config.adapter_name}_3", :"#{config.adapter_name}_4"}
@@ -190,9 +190,20 @@ defmodule Phoenix.PubSubTest do
   @tag pool_size: 3
   test "Registry partitions are configured with the same pool size as PubSub if not specified",
        config do
-    assert {:duplicate, 3, _} = :ets.lookup_element(config.pubsub, -2, 2)
+    assert_ets_duplicate_count(config.pubsub, 3)
 
     assert :persistent_term.get(config.adapter_name) ==
       {config.adapter_name, :"#{config.adapter_name}_2", :"#{config.adapter_name}_3"}
   end
+
+  defp assert_ets_duplicate_count(pubsub, count) do
+    result = :ets.lookup_element(pubsub, -2, 2)
+
+    case System.otp_release() do
+      otp when otp >= "28" ->
+        assert {{:duplicate, :pid}, ^count, _} = result
+      _ ->
+        assert {:duplicate, ^count, _} = result
+    end
+  end
 end