Issue opening Final Cut Pro

This means exactlt what it says: you have a plug-in that is not compatible with your version of FCP and/or macOS.

Did you ever have mO2 installed on your mac?

Did you recently update FCP and/or your OS?

I don't think that this plug-in has a compatible update, but check with the manufacturer.

In the meantime, close FCP, and look under

/Library/Plug-Ins/FxPlug

or

~/Library/Plug-Ins/FxPlug

and see if there is a "Separator" folder there.

If so, move it out of the folder; park it somewhere temporarily, in case you are not ready to get rid of it completely; then start FCP again.

I have not used mO2.

Maybe someone who has can give the correct instructions.

In the meantime, you may want to check also under these locations:

/Library/Application Support/Final Cut Pro

~/Library/Application Support/Final Cut Pro