Hi!
I started experimenting with Unreal Engine 5s Lumen to create a cave environment using Quixel Assets, but I’m facing some weird lighting issues, as you can see here in the Video:
Do you have an idea on how to get rid of these artifacts and lighting changes, as the camera angle changes?
Thanks already and best regards! 
What’s the Lumen Scene look like?
As far as I know those are commonly seen when using Lumen in software mode.
I believe this may occur when you are trying to see weak light bounce, I guess you can try to increase sun intensity. Real world sun may be up to 120 000 LUX, so basically you can experiment with vales between 1 and 120 000 LUX, but be aware it may break other things like height fog which needs to be adjusted right after. You may need to compensate light differences with exposure in post process.
Also you can increase final gather quality and lumen scene detail in post process, I like to keep it at 2.
I think you might be seeing the exact same issue i am seeing, only i was using a HDR map for my ambient light source… GI Changes as camera moves (Lumen GI)
I dont have a solution yet, but i dont want to use any post-processing as all that will be done in Nuke after i just need more GI to be more accurate…