I don't think they can do that on their own, can they? There's still an EU wide rule on DST. They never revoked it, AFAIK.
I'm not sure however what's the process of getting this actually implemented.
https://european-union.europa.eu/institutions-law-budget/ins...
Correct me if Im wrong. Its really hard to understand how EU works, even for us on the inside.
A poll where something like 2/3rds of the responses came from Germany (where somehow that topic had become a particularly hot issue), even though it only accounted for approximately 1/6th of the EU population pre-Brexit.