Basically, when Opera GX starts and tries to load certain fonts or render parts of the browser interface, Chromium can hit a fatal error in its font handling code. When that happens, Opera GX crashes, tries to reopen itself, crashes again, and eventually shuts down. That’s why you can get stuck in a loop of the browser opening and closing several times.

This also explains why recovering or completely reinstalling Opera GX may not fix it: if the problem is caused by the new Chromium/Opera build itself, reinstalling the same version just installs the same bug again.

There are several recent reports from other Opera GX users experiencing very similar crashes after the latest update. Opera has also released a newer Chromium/Opera build for its regular browser that includes crash fixes, so hopefully the GX version will receive a similar fix soon.

For now, I think the best option is to wait for Opera to release a new Opera GX update that fixes the crash. I wouldn’t keep reinstalling the browser repeatedly, since that probably won’t solve the underlying problem.