I assume you mean the Opera Menu button (the logo at the top left) turning red to let you know there's an update? And, sometimes when you click the menu, there's a "Get the latest security update" item with a red dot in the menu?
If so, it's because there's an extra check in Opera itself (separate from the updater) that notifies you about updates. This check was never disabled in the last build(s) of Opera 95 for when running on now-unsupported systems. So, you'll always get that notification eventually, even if you disable the updater and Opera's autoupdate scheduled tasks. The only way to not get that update in Opera 95 is to block the server(s) Opera uses for that specific check.
You can see https://www.reddit.com/r/operabrowser/wiki/opera/disable_updates_windows/ for how to disable the updater program, the autoupdate scheduled tasks, update checking in general (with the --disable-update command-line switch) and how to block Opera's update servers.
If that doesn't all do the trick, there's probably another updater server not in the suggested block list that your Opera in your location is connecting to.
