[Q: Screen dimming is continuously maintained even though I removed Galaxy S10 from my face during calls]
A: Samsung is aware of this issue which may appear on some limited Galaxy S10 device and this problem has already been resolved with latest software(SCA or later version) update. We are scheduled to release this version at earliest possible for global countries.
Depending on the country and carrier, available date for new software may differ.
Therefore please check for updates to your device SW regularly via the Smart Switch PC or FOTA.