Flickering of sorts on Reflections

Hey all,

After upgrading my project from 4.26 to 5.1, I am getting a weird flickering on some materials, also resulting in the scene being way heavier on the GPU.

It also happens directly in the UE editor (not just in play mode)

Here is an example: Dropbox - LiveLoopsMain_51 - Unreal Editor 2023-01-25 10-36-15.mp4 - Simplify your life
(you can see it happening on the metal wall on the left, it happens on various materials, rough or shiny)

The game was on Screenspace before, still is now, what can be the cause of this change?
Both GI + Reflections are set to screenspace.

On 4.26 the flickering doesn’t happen.

UPDATE: It was the Global Illumination settings ScreenSpace BETA that are causing it, in UE4.26 it didn’t exist.

Disabling it (set to None) solved the issue.