only in patch2:
unchanged:
--- a/core/modules/user/tests/src/Kernel/Migrate/d6/MigrateUserTest.php
+++ b/core/modules/user/tests/src/Kernel/Migrate/d6/MigrateUserTest.php
@@ -101,7 +101,7 @@ public function testUser() {
       $this->assertSame($source->name, $user->label());
       $this->assertSame($source->mail, $user->getEmail());
       $this->assertSame($source->created, $user->getCreatedTime());
-      $this->assertSame($source->access, $user->getLastAccessedTime());
+      $this->assertSame((int) $source->access, $user->getLastAccessedTime());
       $this->assertSame($source->login, $user->getLastLoginTime());
       $is_blocked = $source->status == 0;
       $this->assertSame($is_blocked, $user->isBlocked());