Summary

You might contain contain multiple tabs in the issue creation screen, and each of those might contain required fields.

Currently you cannot tell which tabs might contain required fields unless you access each one of them.

Suggestion

Make it so the tabs that contain required fields are highlighted. A possible approach would be to make it similar to Jira Server/Datacenter:

Workaround

If you happen to have too many tabs with required fields, consider using a message field in the default tab to warn users about the existence of required fields in some tabs: