My MBP16 m2 Max 2023 has got the same issue on Sonoma. I use a command to watch the power adapter status. Save the following shell codes into a file named power.sh #!/bin/sh /usr/sbin/ioreg -r -bc AppleSmartBattery | /usr/bin/grep -i "AppleRawAdapterDetails" then execute the following command to make power.sh executable: chmod +x power.sh then execute power.sh ./power.sh For my MBP now, which the power adapter is connected to a usb-c hub and the hub is connected to the usb-c port of MBP. The full power of the adapter is 140W, while power.sh outputs the following "AppleRawAdapterDetails" = ({"IsWireless"=No,"AdapterID"=0,"AdapterVoltage"=20000,"FamilyCode"=18446744073172697098,"UsbHvcHvcIndex"=4,"Watts"=60,"UsbHvcMenu"=({"Index"=0,"MaxCurrent"=3000,"MaxVoltage"=5000},{"Index"=1,"MaxCurrent"=3000,"MaxVoltage"=9000},{"Index"=2,"MaxCurrent"=3000,"MaxVoltage"=12000},{"Index"=3,"MaxCurrent"=3000,"MaxVoltage"=15000},{"Index"=4,"MaxCurrent"=3000,"MaxVoltage"=20000}),"Current"=3000,"PMUConfiguration"=3000}) Obviously, the max power of my MBP is 140 Watts, and the current adapter just can provide 60 Watts. So if I run some software with heavy load on MBP, the battery drains. However, things do not go such easy. Even when I connect the original power adapter with a mag-safe power cord, the battery drains slowly when the MBP is running. When I click the battery icon on the status bar and select the menu item "charge the battery", it seems the battery stops drain and started to be charged. I believe this is a bug of Sonoma. Hope apple solve it ASAP.