they require all bank statements for 6 months, you dont need to maintain that balance all they time though, just make sure statements are complete for 6 months. They do check that throughly.
I went to the consulate in Saigon (HCMC) in April this year with about 10 pages in my passport that contained also Covid related stamps (not only). They have a long list of requirements (ie. bank statements for several month, booking/housing confirmation, flights, etc.) and want you to book an appointement in advance online, which needs to be booked about 10 days in advance to "gurantee" a slot.
As I met all hard requirements, they did issue my visa without anymore hassle than the mentioned. In consequence it is a good optiion in my oppinion if you are well prepared.
Be advised that I got pulled out of line upon returning to Bangkok anyways. With the help of my thai girlfriend they let me in, but made clear it will be the last time on a simple tourist visa (even I went back to Europe for 3-4 months in summer beetween my stays in Thailand.)
I will fly to Saigon, Ho Chi Min first weekend of April to get a tourist visa in Saigon, travel the country for a week and return before Songkran. I have an appointement for Tourist Visa at Saigon early April, which you need to book IN ADVANCE, When I made the appointement in mid March that month of March was allready fully booked, so people might need to book about 2 weeks in advance. Just showing up at that consulate is NOT possible.