Usually ad's only appear if a person has inadvertently clicked on a link or downloaded an app that has them built in.
Try clearing the cache in the camera app via Settings > Apps > Camera > Storage > Clear Cache.
Also try > Clear Cache Files from the phone's System Partition Section > https://www.samsung.com/uk/support/mobile-devices/how-do-i-clear-the-cache-on-my-device/ You may need to insert your earphones or hook upto a powered On Laptop to access the Clear Partition Section. This may help with lag or stutters as this clears the phone of old/unused or broken cache files.There is also a Repair Apps option in the Menu System too.
Daily Driver > Samsung Galaxy s²³ Ultra 512Gb in Phantom Black.The advice I offer is my own and does not represent Samsung’s position. I'm here to help. " This is the way. "