Post Process Ambient Occlusion Grain

Hi! I’m Using Unreal 5.5 with Forward Rendering, MSAA 8x, because I’m making a VR games and having not too much FPS. But I have this “grain” effect in the SSAO since I moved out from TSR. Is there an option to fix this horrible effect ? I’ts ruining the game experience. I changed the AO quality to 100 and the grain is like in the picture.

Thank’s very much!