No problems the first two weeks, I recently turned on and made some Bixby Routines and now my phone won't get a full charge overnight & I wake up to it being extremely hot. This morning there was a temperature warning and it had stopped charging because of that. I have Mobile Hotspot, Data, Bluetooth & Always On display on. Wifi off and everything else as it. I've also been falling asleep with the Galaxy Buds streaming music. I turned off just Mobile Hotspot and it didn't help, I imagine turning off the whole routine would fix this but I shouldn't have to, am I overworking it or should it work?
Have you tried a different charger? Have you charged the device with multiple outlets? Does it allow you to reach a full charge when the device is placed into safe mode?
You can try these steps, your phone won't be wiped. Enter settings, then type reset into the bar. Do reset settings, accessibility, and network. Reboot afterwards.
Also, are you using a wireless charger without a fan? It produces more heat than wired.