It's weird that request activation action triggers /var/workflow/models/request_for_activation1, but not original one /var/workflow/models/request_for_activation.
Please check if you have /conf/global/settings/workflow/models/request_for_activation1. If you have it, you will need to sync it. Open /editor.html/conf/global/settings/workflow/models/request_for_activation1.html and click "Sync" on the top-right side.
One thing that comes to my mind that you might have overridden WF model for request activation action. Check if you have /apps/wcm/core/content/sites/publishpagewizard. See more: https://blogs.perficient.com/2019/02/11/customizing-request-for-activation-deactivation-wizards-aem-6/