The only subreddit you should trust is /r/cryptohelp if you have questions pertaining to how to use dexes, cexes, lost your private keys, and need help with pretty much anything related to crypto. Even in that subreddit, you should know that no one can DM you with helpful info and anyone who tells you that they can help you recover stolen / lost crypto is lying to you.

There is a somewhat well written post that redirects to another subreddit informing people of the dangers of trading crypto on dexes and comingling funds with from centralized exchanges and users of these platforms not being able to sell their crypto on centralized exchange as a result. This is embellishing a story to create an oh-so-slight amount of fear in the readers of that post. They also state that if you bought an NFT with clean funds, then someone who may have bought the NFT before you with "dirty" funds could make your crypto "tainted" and cannot be sold on a centralized exchange. This is a scam. Do not share the post here. It links to a sub that cannot be trusted and has less than 100 followers.

There's another scam going around where what looks like an ordinary Redditor will say something like, "Hey guys. I can't move a few hundred USDT or 10,000 USDT. Here are the private keys to this wallet:" Those are drainers. They are intentionally trying to trick you into importing the wallet, and putting gas funds (like 20 bucks of ETH / MATIC / TRX), while they have a bot that immediately moves those funds out of the wallet a fraction of a second after the funds arrive. Newbies to crypto might try to move a large amount to that wallet to their (extremely unfortunate) detriment.

Stay safe.