I noticed this issue too.
When I try to impersonate a user it does weird things. At first it does nothing, after trying a few things, like reloading the page, I finally end up being in impersonate mode.
But it displays an error toaster with "[object] [object]" and I can't do anything even logout.
When I try to go back to the login page, the page stays blank with JS errors:

I'm running brave browser, maybe something is blocked by built in brave anti-sh1t ads.
EDIT: Disabling brave shields on the pages doesn't help. Also I noticed these errors in the JS console when trying to impersonate in the first place:

EDIT2:
Tried with Edge and got the same issue.
Tried with Firefox and the issue is different. With Firefox, the browser tells me it has blocked a popup and asks me if I want to allow it. When I allow it, the impersonation works correctly.