Various problems with Contribution pages and payment processors since upgrading to CiviCRM 5.65 (from 5.49). In the PHP error log I see:
PHP Fatal error: Uncaught Error: Class 'Civi\Api4\PaymentProcessor' not found in /home/footprk1/public_html/wp-content/plugins/civicrm/civicrm/CRM/Admin/Page/PaymentProcessor.php:65
PHP Fatal error: Uncaught Error: Class 'Civi\Api4\ContributionPage' not found in /home/footprk1/public_html/wp-content/plugins/civicrm/civicrm/CRM/Utils/System/WordPress.php:1579
I'm noticing that these classes seem to have moved from plugins/civicrm/civicrm/Civi/Api4 to plugins/civicrm/civicrm/ext/civi_contribute/Civi/Api4. Seems like maybe the system is still looking in the old directory for these classes?