2 answers
The big ones that stick around are Tandem, ConversationExchange, and language-specific Discord communities tied to subreddits like r/languagelearning - those tend to have active voice channels where you can actually practice instead of just typing. Honestly your best bet is searching "[language you want] Discord" and checking which servers have mods actually enforcing the "no English" rule in practice rooms, because a lot of them claim that but don't enforce it. Look for ones with scheduled conversation hours and native speaker verification, since that usually means they're serious about quality over just being a hangout spot.
most of those listed are solid, though tandem's actually more of an app than discord - the reddit-linked communities are where you'll find the real voice channel activity, so those are worth joining if you haven't yet. before jumping in though, what language are you targeting, and are you looking more for casual conversation or structured lessons?
Your answer
Log into answer.