I've suddenly just started getting this message frequently appearing on my S8 phone. I didn't recently install a new app so I've no idea which one and why it's asking.
Does this appear when you open an app? If so then it is related to that specific app. If it appears randomly then it could be an app working in the background. You could try restarting your phone or clearing the cached data (go to settings, storage, then select cached data) to see if it helps get rid of it.
To see which apps are running in the background, go to developer options in settings. If it doesn't exist then you will need to activate it, go to "about phone" then tap on "build number" several times.