This issue seems to be related to this thread:
[Compilation] Music Player Not Showing Music Services

Note: This thread was posted first.

@msanchez1042 Have you tried clicking "Recover..." on the bottom?
Please ensure that you also select "Keep my data and only reset Opera settings."

This resolved the issue for me.

By going into the settings and clicking onto "Update & Recovery"

Followed up with clicking on "Recover" seems to have fixed this issue.

Ok Opera GX!
You got me!

The Player functionality worked fine last week, and I have been listening on Youtube Music for over a year now.

I am currently on the latest version at the time of posting this, restarted Opera GX a few times.
Waiting also does nothing and there seems to be no way for me to open DevTools to clear the cache.

Version: LVL 5 Core 109.0.5097.70

I will attempt to run "Recover" now.