Thanks for reaching out.
Can you give a bit more detail on the symptoms you are experiencing so I can better assist you? Are you using the stock camera app when this message pops up?
Settings / Device Care / Battery / Battery Settings top right / Sleeping Apps....remove camera from the list of sleeping apps. Reboot device if didnt stop.
That's what solved it for me
Another user susgested this and it worked for me:
"Go to Settings, device care, tap battery, then look for the camrea app, and make sure put to sleep option is turned off."