I've had this happen sometimes with Spotify - something that helps me temporarily is to remove all the background process(all the apps running in the background) to help me with it. my case could be different from you - It definitely could be 1000 things, as @mytech said. And its possible it could definitely be a power optimization issue(thanks @shaggyskunk1)
If you're still stuck after trying all these things out - I recommend you access the "Get help" section in the bottom tab of Samsung Members - you can get direct access to help there. Or just let this thread know and we can keep probing into this issue.
