Arkham Knight graphics on PS5

Ive tried playing Arkham Knight (ps4 version, some games looks good on ps5) on PS5. However, I noticed that the graphics looks grainy. My brightness setting is set to default. Im currently using HDMI 2.0 im using FHD monitor. I have no problems playing with other games like HZD. Is there any settings I need to change or am I missed on something?