One thing worth trying, in addition to the steps above, is to clear the stored data for that exact site rather than just toggling the permission. In Opera, go to the failing page, tap the padlock in the address bar, open Site settings, then clear the site data and reset the location permission there. Then close the tab completely and open the /tallinn page directly, rather than navigating to it from the main page, so Opera asks for location fresh on that page.

It is also worth checking the Android side in more detail: in Settings > Location, make sure Opera is set to precise location rather than approximate, and that Google Location Accuracy and Wi-Fi scanning are on. Some map sites need that extra accuracy signal, and an approximate fix can be rejected outright, which would explain why Google Maps still works while smaller sites report the request as denied.

If it still fails after that, noting whether the prompt appears at all on the failing page, or whether the site reports denied without any prompt, would help narrow it down — the first points to a stored site decision, the second to Opera or Android blocking the request before it reaches you.

A few things worth trying, in order:

• In Android Settings > Apps > Opera > Permissions, check Location is allowed while using the app and that precise location is switched on.
• In Opera, check Settings > Site settings > Location for the sites that fail, set them to Allow, then clear the stored data for one failing site and try again, accepting the prompt when it appears.
• Switch off Opera's built-in VPN and ad blocker for a failing site and test again, in case either is getting in the way of the location request.
• Note whether the failing pages are on HTTPS and whether the map itself is embedded from another domain — that domain would need permission as well.
• Try the same pages in a private tab, and compare with Chrome on the same phone. If they work in Chrome, that points to an Opera permission or a blocked third-party origin rather than the phone's own location settings, so it is worth reporting with your Opera and Android versions and the exact failing addresses.