Solend is not a DEX. It is for borrowing against assets. https://aave.com/ is a better lending protocol. Solend has a questionable history, and is closely associated with FTX, which is why the SOL token is down so much.
Patrick gives a good description of the problems in that tweet thread, and why it is affected.
Solend is a major one that's currently falling over.. and apparently just disappeared $6M worth of users' assets;
https://twitter.com/patio11/status/1590725993324777472