I've been having a lotta discussions around the Ukrianian Russian conflict and exploring the history with my friend. But they keep bringing up a claim that neither I nor they can find the source for.

The Claim is; Russia, Donetsk, Crimea and Luhansk at some point have suppressed the Ukrainian language. Specifically Since 2014.

Ukraines suppression of Russian is not contested, nor is Putins position on Ukranian identity.

Is there any proof of such a thing happening? I've taken the discussions previously as if its true because I don't really know enough about the conflict but after extensive searching I cant find anything.