Comment by thephyber

Passwords are more secure if they are higher entropy, so it makes sense to support a larger variety of characters, Czech or emoji.

It seems paramount that the OS should not allow password input of any characters which it theater takes away. At the very minimum if this is absolutely necessary to make this breaking change, the user should be warned several times that a character in the password is no longer valid and maybe even prevent the OS from upgrading before the password is changed to a forward-compatible one.