Yeah. This is bad. It's basically unusable after update to 86.0.4240.75-1 . Here's what mine looks like. Note that there are only two Chrome windows open-- the one in the bottom right is a visual artifact, as is the portion of my desktop surrounding it-- those are actually being displayed as the contents of the second Chrome windows, which you can see the border of in the middle. Unfortunately, I don't have time to wait for an update. I need it to work today, so I can fix other people's issues. Lovely.

Only way I know to triage until they fix it in a future update is to uninstall and install an older version.
I need it to work now, like right now, so downloaded closest stable version I could find, closed Chrome and uninstalled buggy version using Synaptic; closed Synaptic, and installed older version (84.xxx).
This worked to squash the bug, at risk of recently known security exploits. Yay! Hopefully they'll have a patch soon.
Oh, yeah-- this is where I got the old version:
https://www.slimjet.com/chrome/google-chrome-old-version.php
Specifically, this one:
https://www.slimjet.com/chrome/download-chrome.php?file=files%2F84.0.4147.135%2FChromeStandaloneSetup.exe
And this is where I found the reference to SlimJim:
https://stackoverflow.com/questions/11408325/download-older-versions-of-google-chrome-for-linux