looks like rendering adblockers extensions obsolete with manifest-v3 was not enough so now they try to implement DRM into the browser giving the ability to any website to refuse traffic to you if you don't run a complaint browser ( cough...firefox )
here is an article in hacker news since i'm sure they can explain this to you better than i.
and also some github docs
Bank sites don't necessarily need to want to block ads to implement something like this. They will just see the headlines that say "this is more secure" and that will be enough for them to buy in to it.