Pleasant experience at Chiang Mai immigration yesterday for the 60 day covid extension.
They have all the forms outside and 2 helpers who speak fluent English, after you fill out the TM7 and the various declaration forms the helpers check them and your photocopies over for you then give you a number. If you have the online / mobile print out of the TM30 you'll need to convert this to an in person notification which goes in your passport - they just directed me to a building to get it done and it took 5 minutes.
They weren't interested in the letter from the embassy or the landlords I.d. They are stamping for 15 days and you come back for the next 45.
Once inside the whole process takes about 15 minutes. The staff were quite nice, and dare I say it, almost friendly?
I was on a 3 month education visa, and they did want the cancellation letter from my school.