White wall looks patchy only from an angle (one wall out of four in the room)

[Fiasopia]

Hello, thank you for taking an interest in my post!
My partner is re-painting our kitchen to freshen it up, white on top of white. 3 out of 4 walls in the room are fine but one wall has a strange problem. When viewed from an angle the paint job looks very patchy, but when viewed straight on it looks fine. She has done two coats on the wall already and is layering it on thick with small rollers of a medium density.
It's a little hard to capture but I have put attached two pictures and here is a video as well.
I wondered if it might be damp but it seems very strange that it is only from an angle that it seems noticable. Any ideas/speculation/experience/support would be very welcome!

Thank you!

 

[DiyNutJob]

Is it to do with the wall not being flat? If that is the case, sanding will help.

 

[Fiasopia]

Yeah, that was the initial thought of my partner but it's pretty darn smooth so I am not totally sure. I think trying to sand it sounds like a good idea though and something we will try - thank you! Thinking to get some different paint as well.