Yes, don't launch Opus elevated. The text is there to warn you, because it will break Explorer Replacement and some other things.
Opus should be run normally, and then use the UAC support or Admin Mode button within the program if you need to elevate actions or individual windows.
See Why NOT to run Opus as Administrator under UAC for more detail.
All I did was install version 12.9 and the text appeared.
See the FAQ, it explains what to look for to stop it happening.
Either the exe is set to run as admin or it is being launched by something which is already admin.
If this is the same session as when you did the upgrade, the elevated install process may have launched DOPUS, at the end of install, as admin.
The installer will normally launch Opus unelevated. It shouldn't be that, unless the installer was run in an unusual way or the system is in an unusual state (e.g. the whole desktop explorer.exe process is elevated).
Thank you, that was the problem. Exiting Dopus and loading it again, fixed the problem.
It can happen if the installer is launched as Administrator, instead of running the installer normally and allowing it to elevate itself when it needs to. (The installer will run Opus in the same way it was launched itself.)
Maybe that's what was done?