Using # symbol and another key activates... I don't know what.

On my Intel iMac with macOS Ventura 13.6 / Apple Support took care of a keyboard problem yesterday, but then THIS happened.

This morning, I wanted to make sure the original keyboard problem (skipping certain letters) was gone, and started typing all the rows on the key, this happened whenever I hit hashtag and the next key, the $.

and then this showed..

or.. a choice of either of them

What is this, and what do I even call it? as I didn't do it! (NOTE: I can’t discount the fact that “cats walking keyboards” can activate keyboard sequences, so now I have a clear plastic barrier covering keyboard just in case.)

And while I was taking screenshot of this, the Mac logged me out, with this, on of several of my custom wallpapers, this one optical illusionist / magician Jerry Andrus.