emissive material creates flickering lighting artifacts

[Arkiras]

You cannot light a scene with small emissives and expect good results, you must use actor lightsources (point/spot/rect)

UE5 Light Material Flickering issue

You are probably going to have to lower the emissive intensity of your material or increase the brightness of your light. 1 candela is extremely dim… You may not be able to get rid of it entirely as this is just the nature of having small bright emissives in your scene, not enough of Lumens rays will hit the emissive surface and so it will not converge to a stable result.