Currenlty, JSW team managed software projects you can go to the Issue Types and add custom fields but you can also search for any usable field and for instance the "Requested Participant(s)" system field is specific to Jira Service Management projects and having it appear as an option in Jira Software projects can be confusing and doesn't work the same as it would also display JSM customer accounts which can cause issues with notifications.

Looking to only show fields that are specific to the type of team managed project.