Unfortunately this is not unusual for the 2016-2020 USB-C Intel Macs. I've even seen it happen with a brand new Apple OEM battery (official Apple repair). That tells me that most likely the Logic Board believes it has lost contact with the battery since a power adapter is usually needed to power on these 2016-2020 USB-C Intel Macs after having the battery disconnected. I never bothered to investigate further because my organization's users were not bothering support about it.....this is something I personally observed while troubleshooting & repairing my organization's Macs.
If it is occurring frequently and an SMC Reset (Intel Macs only....and make sure to follow the T2 instructions) doesn't help, then it may indicate a bad battery, or it could be a Logic Board issue if the battery is healthy. Unfortunately it is not easy to determine if the battery is truly still healthy since the Battery Condition reported by macOS is not reliable enough for diagnosing something like this since a "Normal" condition status is irrelevant (if "Service Recommended" is shown, then that means the battery needs replaced). Even the Apple Diagnostics doesn't catch many of the battery failures....only a failing diagnostic result is useful. Unfortunately most techs don't know how to perform a more thorough evaluation of the battery.
FYI, most Lithium Batteries need to be replaced between 3 - 5 years although there are always some exceptions.
