If you believe Google Maps, then Opera is often not terminating in the region (Americas, Asia, or Europe) that it claims to be. Either some of the exit nodes have been hijacked and forwarded elsewhere, or Google is using incoming data to infer (or hallucinate) where the exit node lives in geospace. I suggest discussing this observation with your VPN provider before it causes reputational damage, notwithstanding that it may very well be an illusion. Even so, Google's inferential tendencies would provide good cover for actual hijacking, so please inspect carefully.

Make sure you're using Opera with a VPN connection set to start automatically. Then quit Opera, unplug from the internet, restart Opera, and observe that the VPN indicator turns yellow (pending). Now terminate Opera. Leave the internet disconnected. Click on the Opera icon to restart. It never actually launches because the previous session never fully terminated. Unless you happen know how to kill all of Opera's processes without introducing data corruption or an inconsistent state, then you have no safe choice but to reboot the entire OS. This is a rather awkward workaround, so thanks in advance for looking into this.

If you try to install an extension in the Linux desktop version (and probably any version), you can't do so if your connection latency is too high.

If you can't reproduce this, then try again on a distant VPN exit node. The nginx server gives up and throws 504 after several seconds. ("504 Gateway Time-out nginx")

This started just today. My guess is that the extensions server in my part of the world went down, so the CDN is rolling over to some more distant server, which then times out due to excessive latency.

The high high latency and tiny bandwidth of Opera's free VPN often causes timeouts like this. Like I could barely manage to get the hCaptcha to come up when I registered for this support forum itself, which I had to retry repeatedly. That's not the VPN's fault (because it's free!) but somebody might want to fix the forum interface.