Cinny (yet another web client for Matrix)
Did not crash or get disconnected as far I kept it running for a couple hours.
SchildiChat (element-based client)
This is a rather heavy thing, which of course it works perfectly on say, G**gle Chrom|e|ium obviously, and I even expected it to crash the webview, but to my surprise, it only ran a little slow, but otherwise worked fine.
Telegram Web X
I get instantly disconnected from it, and runs slow-ish as well, because it's too fancy (i'd say extremely) and I don't really like fancy stuff if it is hardly useful.