Maybe a similar situation and may now be resolved:
2021 MacBook Pro 14" with default power adapter
Battery is showing only 1% and the battery icon is an AC plug instead of a lightning bolt that normally means charging.
Battery otherwise looks great in System Information.
When power adapter connected (MagSafe) shows orange, blinks once, charging "chime" is heard, then blinks off, then goes back to steady orange. Meaning: plugged in but not charging.
Connected power adapter with USB-C cable instead. No improvement. No charging.
Tried restarting the computer and tried in rescue mode also. No charging.
Resetting the SMC not really applicable because it is an M1 Mac. But tried the procedure for Intel Macs anyway. No charging.
Tried leaving the power adapter connected with screen open or closed. No charging.
Updated operating system and tried changing battery "optimized" charging setting in System Preferences. No charging.
Went to Apple Store for an official service appointment. They could not get it working. They tried a different power adapter, cables and other things. Computer would operate on AC power but not on battery and would not charge battery.
Computer has never left a desk since it was new. Could not think off anything that could have caused this. Apple said they need to service the computer and there is something wrong with the battery possibly. Apple sent me a box to ship my computer for service.
Before receiving the box, the computer was sitting unplugged and off for 2 days. I plugged in the computer to make sure I did not need to back up anything further before shipping the computer.
BUT NOW, the battery is charging. Icon shows a lightning bolt. Battery % is increasing,. Says 2+ hours until fully charged. I will wait until later and see if this is back working again and if charging is reliable.
If this is now fixed, I have some possible explanations. The 1% charge needed to get to 0% which could take a couple days with the computer sitting unplugged, which allowed the power management software/firmware to work as intended again. Perhaps a small bug in the power management system that can be fixed by an operating system update in the future.
In my case, the computer had hardly been used on battery at all. It was used with an external monitor and keyboard. When not in use, I usually had disconnected the MagSafe adapter. Perhaps the "optimized" battery setting in System Preferences started to avoid charging the battery and it ended up becoming a problem somehow that the system would not recover from unless the battery got below 1% by sitting for a couple days?
Hopefully this is fixed. Should know in a day or so if battery charging seems normal. Hope this helps someone.