Flickering black squares during ultimatum

Zone: Any, only during ultimatums.
Print screen (taken from video below): https://imgur.com/a/K7NpqE3
Video: https://www.youtube.com/watch?v=oeuijuImAkw

PC Specs:
Processor: AMD Ryzen 5 5600x
GPU: AMD Radeon 6800XT (latest Stable drivers: 21.3.1)
OS: Windows 10 Home version 20H2

Edit:
Renderer DX11, but same issues on Vulkan