CREATE COLLATION must be specified

Testing on the PG15 beta, I'm getting new failures when trying to create a collation:

CREATE COLLATION some_collation (LC_COLLATE = 'en-u-ks-primary',
    LC_CTYPE = 'en-u-ks-primary',
    PROVIDER = icu,
    DETERMINISTIC = False
);

This works on PG14, but on PG15 it errors with 'parameter "locale" must be specified'.

I wanted to make sure this breaking change is intentional (it doesn't seem documented in the release notes or in the docs for CREATE COLLATION).

Shay