Hey there @123SarahharaS321! Welcome back to the community! So the flickering you’re seeing is Lumen trying to find a good final gather solution. This will continue occurring on lower settings often. If you’re doing a solid render this thread here can help (it can also help for game settings but it’s mostly for non real time rendering)
Other’s have stated that increasing final gather settings inside your post processing and disabling Temporal AA in project settings could alleviate some of the flicker.