, a bit "visa/extension dependent" though. Y'r right concerning "if they found out living in Thailand on wrong visa". But the risk of refusing entry, is much much higher when you had Covid extensions (Unable to travel home). It is strange ofcourse when you leave the country and then come back after a couple of weeks. There are a lot of people refused entry when they had covid extension and then come back quickly...
, not 100% sure, but apparently you need a background check certificate from Thailand for a move to another country. You have to do this by all requirements mentioned in y'r picture.
That "letter from the Embassy........" is I think a letter for wat reason you need that Thai background check certificate. Because there are ofcourse no Thai Embassies in Thailand almost sure it has to be a letter from y'r own country Embassy (or government ?). Think they presume people are still in Thailand, requesting this.
. It's an O visa. These ones I did not see for a long time, because landborders are closed and re-entry via air, is difficult because every time you need the entry requirements for Thailand. The visa is valid for 1 year and let you stay for 90 days. After those 90 days, people go to another country and every time you enter Thailand, you got another 90 days. So if you just did it before the experation date of the visa (so after 1 year), you could get almost a year and 3 months out of it.
Open fixed deposit account with an amount you want to use as a limit for your mastercard. Then most banks will give you a mastercard. (i say mastercard, because of course it is no real 'creditcard' then, because you already deposited the money in a fixed deposit account)