New php dependencies?

[Nils160988]

After upgrade from 19 beta 2 to 19 beta 4, admin warnings complain about missing php dependencies (bcmath and gmp). For beta 2, no warnings appeared.
bcmath is not mentioned in the documentation at all and gmp is only recommended in combination with sftp.
If this (new?) requirement is intended, it should be mentioned in the documentation or release notes. Maybe I just missed it, then it would be nice if someone can show me.

[kesselb]

cc @MorrisJobke @rullzer

[rullzer]

It is needed for the passwordless auth.
Adding it to the 19 docs is still on my todo

closing possible through nextcloud/documentation#2040