@Vincent **************
you got your wires crossed slightly.
Immigrations doesn't have a dog in this fight, it's the Ministry of Foreign Affairs office <- the people that run the consulates and issue the Certificates of Entry that control the length you need to be insured for.
The length of time you need to be covered on covid insurance has nothing at all to do with the VISA <- the sticker from the thai consulate.
EXAMPLEZ:
1 - If you have a year long, multi-entry Non-O visa, while the visa sticker itself is valid for a year you can only get stamped in on it for 90 days each entry <- meaning you would only need 90 days of covid insurance (the amount of time you'll get stamped in for
2 - If you had a year long, multi-entry Non-O-A (long stay) visa, while the visa sticker itself is valid for a year your entry stamp on that type of visa is also a year <- meaning you would need to carry a year of covid insurance (and the mandatory health insurance required for that visa type).
3 - IF you had a 90 day single entry tourist visa, while the visa sticker itself is valid for 90 days your entry stamp on that visa is only for 60 days <- meaning you'd need 60 days of covid insurance.