Got it, someone from the official ppsspp-forum had the final hint.
I share this here for everyone running in the same issue (which should happen if you updated recently):

"RE: graphical issues since last update
Turn off the vertex cache setting.

It used to be accidentally disabled in code, but we re-enabled it recently. It seems to be malfunctioning on some devices now, though. It was accidentally broken for several stable versions."

@cagusch Have you tried it on lr-duckstation?

Also, not saying that that's the case, but it is quite normal for games to reduce polygon count and drawing distance when rendering split screen. What's the atual behavior you're observing?

IT WAS THE ROM DUMP!!!!!!! I TRIED THE SAME ROM ON MY PHONE AND ALL THE GLITHCHES ARE THERE!!!!!

I'm pretty positive that the romsets are correct with the emu version.
I've ordered a 3B+, should come in the mail tomorrow,was hoping to be able to find a use on the old rpi but i guess it's gonna be something else.

Thanks

@zerojay

Perfect, if there is a pull request for it I can wait for it to be incorporated into a future update and I can update. For now, lr-reicast seems to actually be working pretty well for the couple of games i've tested.

I will have a look for the pre-compiled binary though and perhaps give it a try.

Cheers

do you have the enhanced graphics stuff turned on? it is quite buggy with certain 2d elements.

It's probably now saved as "on" in their set-up since they ran it when "on" was the default, and now that option has saved, so they will likely need to switch it off from RGUI.

I thought I had rebuilt the binaries, but perhaps not - I will do that now

@Capt_MorganCreek similar codebase. The Dev of that will likely fix the issue for both when has some time to look into it. It's a RPI issue.

Well, I change from the theme SIMPLE to CARBON. No more problem. I made my new NES thems for the ROMs Hack and it works fine!

Thanks you all!

OK, thanks. Guess I have to bear those glitches then.