Well, in xorg or xrandr there is bug when we rotate the screen in portrait mode on tablets/2-in-1 laptops.
This bug is well know by the xorg team but it wasn’t fixed since 8 years.
so, I uninstalled the xf86-video-intel package but it didn’t change anything. I still have the problem. When I flip the display from landscape mode to portrait mode and from portrait mode to landscape mode, there is a delay and a black screen. It doesn’t appear when I flip the screen from normal to inverted in landscape mode, and from left to right and right to left in portrait mode. This is a ‘bug’ and it has never be fixed by the Xorg/Xrandr Team. Moreover, I’m not the only one to have this problem.
I’m come back to you. A bug report was made for this problem on the xorg gitlab, but nobody don’t care. So, if you have time, can you have a look on it ? All the information are here
Otherwise, can you contact the team charged by xorg or xrandr to talk about this problem ?