Blocking screenshots for certain apps has been like "someone drowned in a lake -> block access to the lake".
The only thing it helps in is helping banks close the tickets when you inform them of a bug and they ask for screenshots and you tell them you can't because their app doesn't allow it, so "… closing this ticket since we received no further input from the customer. Please feel free to reply if you need anything else."
They never tell me to take a photo from another app and I never volunteer to do that because if they reply like this I know they are not going to work on the bug.
It's another case of "I am the legitimate owner of this phone and authenticated into this app, and yet you still want to block me from using it?" modern problem.
The only thing it helps in is helping banks close the tickets when you inform them of a bug and they ask for screenshots and you tell them you can't because their app doesn't allow it, so "… closing this ticket since we received no further input from the customer. Please feel free to reply if you need anything else."
They never tell me to take a photo from another app and I never volunteer to do that because if they reply like this I know they are not going to work on the bug.