Can I complete my 90-day report in Koh Tao if my visa is issued in Bangkok?

There's an immigration office on Koh Tao and they aren't that busy. Go see them and see if you can do it there. Worst that can happen is they say is no and you've wasted a full 15 minutes of your day. If you have the patience, technical know how and an android phone, you could try doing it on line. I managed it recently using Brave browser (not the app}

What's your plan, stay in Koh Tao? return to Bangkok eventually? Renew your extension again? I may get shot for suggesting this, but, missing a 90 day report is very small potatoes, and the dark red zone risks and expenses to get back to Bangkok are plenty. Have you tried to do the report online or via mail? Anyway, personally, I'd rather pay the fine the next time I go to extend if that's the case.

PS..

Ok I saw your reply where you said your returning to Bangkok next week..nvm

when is your 90days report due? Is this your first one?

What kind of extension do you have?

Did you move to Koh Tao, OR are you still living in Bangkok and will return?