Oh, I understand why you asked my visa. You can open Bank account with Bangkok Bank regardless of the visa that you have, but the certificate of residency is non-negotiable. You can't open an account on your own without it unless an agent bribe manager, or manager bribe you.
I am currently getting the marriage extension, so yes, long-term visa. The bank manager is operating fraudulently. Most likely he is used to work with agent so he is by-passing that with you to ask you for a bribe. It's a pretty big bribe because with an agent it will cost you around 5k baht to open a bank account without meeting the requirements. You cannot open a bank account in Bangkok Bank without the certificate of residency (unless with agent or other form of bribe). The certificate of residence is easy to get at immigration, I got it last week. You need to go there and fill a TM30, then ask for residence. You just need the blue book and copy of ID of whoever you are renting from.
I live in Thailand for 10 years and I have no idea what you are referring to. You do not need a visa to enter Thailand unless you are required "visa on arrival" (selective number of countries).
Because until border bounces are possible, they will lose too many foreigners if they remove the Covid extension. You may think that there are a lot of tourists in Thailand right now, but no, very little still. They can't afford to annoy the ones who still rely on Covid extension. When border bounces are back and buses go to borders every day, they will remove Covid extension. For now, people are flying to Phnom Penh to get tourist visa, it's simply not efficient enough so such Covid extensions will remain until border bounce reopens.
Just avoid Suvarnabhumi Airport, enter from Phuket, Chiang Mai, etc. Or if you enter via Suvarnabhumi make sure that you have an agent phone number to call to bribe your way in if they want to denied u.