IF that slip is correct
@Dan***
you were late on the 15th of Dec 2020 :O AND you never noticed that slip in your passport, didn't read it?
I see a trip to your immigration office to find out WHEN your actual 90 day report is/was due
The good news IS, if you're late it's just a 2000baht fine it doesn't go up.
Those are Chaengwattana Stamps so you would go to the Muang Thong Thani Immigration office for your 90 day reporting