Thanks a lot! I managed to fix it, I put a DL190 in the grip and updated the firmware.
I was on 1.14 and the menus and especially the image viewer were quite laggy. After the firmware and the battery in the grip the flickering had stopped. Seems like it was a software issue, although I will not use the grip with AA batteries again seeing as it’s a non Pentax grip and I’ve heard people have had issues with that.
Sorry to have bothered the lot of you with my almost panic levels of writing.
And thanks for the help again!
Hope you have a grwat week and stay safe out there