Is to notify the Thai government of your continued stay within the country. If you leave Thailand during your 90-day report period, it’s void.
Once you come back, your 90 days begins the day you arrive.
For example, if your next 90-day report is at the end of this month (31st Aug) but you decide to visit Vietnam for the weekend, your next 90 days isn’t end of the month, but 89 days when you come back from your vacation.
If you’ve been renewing online and leave the country, your first report back has to be in person again.
There has been lots of warnings and info in the news about stricter banking regulations for 6 months or more now. The deadline to update has passed and anyone who has not done so has been locked out or had their transactions limits reduced.
You say that both your Sim Card and your Bankk have matching names (using the same passport) but the Bank thinks otherwise. Maybe verify which account you are using?
I’m pretty sure anyone living here has one of the included banks, that they then can transfer with no cost once you’ve deposited into supported Thai bank account (wise still charges for transfer to Thai bank though)
This looks like part of their additional crackdown on IML activities. Nothing really convening