@scort: If you press and hold on the Samsung Members app icon > Diagnostics > Cable Charging, and connect to your charger, does this flag any problems at all? If so, do you have access to another compatible charger that you can try to see if the issue persists?
Same issue on S20+ after upgrading now to Android 12..all genuine Samsung fast chargers with new cables stopped working. Tried all tricks here and more with no luck...this is enough to change OEM, renders the phone useless.
Same here with galaxy s10 no fast charging. 3 hours for full charge