You can use emojis as passwords, do you think that's a good idea? They work now, there's a good chance that they won't be the same forever. See what happened to the family emojis
That's just excuses for moronic decisions of trillion dollar companies.
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necessary to make this breaking change, the user should be warned several times that a character in the password is no longer valid and maybe even prevent the OS from upgrading before the password is changed to a forward-compatible one.
It's like they realized that emojis really shouldn't need to deal with color and gender.