Pengilly
This is about the best thing I could have hoped for, so I really hope it doesn't get taken down! (but then again, the for-profit Fandom wiki farm hasn't taken down Breezewiki or other mirror sites yet, so maybe corporations figure this sort of thing isn't worth the effort to take down.๐ค
I mainly lurked on the art and fanfic forums, and considered getting an account when I had the time/had created something worth sharing on there. But when I learned about the disabling of apps to improve accessibility...I started looking for alternatives.
Plus, I don't like the idea of the karma system on there. Supposedly, it reduces the number of trolls and low effort posts, but I've seen it cause people to post ragebait to karma farm on subreddits that reward you with upvotes for making up outrageous stories. I've also seen "debate" subreddits where people downvote people who make good points, but disagree with. Then those people leave, not wanting to be punished on other subreddits that require a high amount of karma to post, leading to "debate" subreddits that are laughably one-sided.
I started looking for alternatives when they added the weird character voices and I started noticing inaccurate pronunciation of kanji in my Japanese course. A lot of people on the message boards recommended Memrise, and it's been great! The official courses contain actual video and audio of native speakers, so I knew for a fact the pronunciation would be correct---even better than the old Duo voices!
There's also user-generated content, too, some of which might not be accurate, but most of the user courses I've found are pretty good. You can even make your own set and publish it.
(I haven't visited the site in a few months, so I can't guarantee it'll be exactly as I found it, but I doubt it has changed much)
And depending on what languages you're studying, you might be able to find some good ones dedicated to your language if you do some digging. For Spanish, I used SpanishDict, and for Japanese, I used Kanshudo (both are freemium, with more restrictions than Memrise)