My wife and I both have the S10 plus and both of our phones are experiencing this same issue. It drains at a rate of approximately 15% an hour. More if I'm using more than just email or texting. I haven't been able to find a solution posted anywhere. If this continues maybe my next phone won't be a Samsung. It would be a shame since we both really like the Galaxy line.
Have you tried wiping the cache partition on your device? Do you experience these symptoms if you test your device in safe mode?