ISSUE RESOLVED FOR ME
I had the same issue, I tried almost all the builds from 2021 and 2022.
At last I had to change my graphics API to ‘Vulkan’ from ‘OpenGLcore’. It worked for me.
Version of Unity = 2022.2.15f
Linux Distro = Linux Mint Cinnamon
Processor = Ryzen 5 3500
Graphics Card = GeForce GT 710
Thankyou so much. This was giving me an aneurysm.
Project Settings->Player->Other Settings->Rendering. Uncheck ‘Auto Graphics API for Linux’, then place Vulkan above OpenGLCore in the list. Required a restart and no more flicker.
2022.2.6f1
Same issue (a gray triangle flickers across half of the screen diagonally) on version 2023.1.0 with OpenGL enabled. Can be fixed by switching to Vulkan API in Player settings. Cannot be fixed by switching color space (still bugs with both Linear and Gamma)
Win 11
i5-1235U (laptop)
integrated graphics Intel Iris Xe
I found another weird solution. Go to NVIDIA Control Panel, Manage 3D settings, Find and select Unity 3D and change “Power management mode” to “Prefer maximum performance”