I understand it's all banks that are affected, yes, and it is a legal requirement, though I have no idea which law other than the one already mentioned earlier in the thread. It's because it's a legal requirement that accounts will be blocked if the ID isn't collected before the deadline. I'm not sure whether the end if April is the legal deadline or an internal one, but the legal deadline must be close because pressure is very high on us all.
"Digitalizado", the ID documents are scanned and the images stored in the bank's computer database. In our place this database is accessible by all branches and is used to verify the identity of customers when withdrawing cash over the counter, for example.