Dunno about 2024, but 2023 G14 explicitly documents it can't work at full power when powered by USB-C, because it's USB-C PD supports only 100W compared to the >200W draw of the system. So it throttles just like macbooks with i9 (but those throttled always because one of the problems was overheating VRMs)
I don't expect max performance gaming on USB-C, but it should at least run as fast as it does on battery alone. It should definitely be able to update a mouse cursor and play an MP3.
This isn't just throttling, it's unusable. And it instantly goes away for a while when you disconnect and reconnect the USB-C power supply, even when gaming etc.
Oh, I fully admit that it could be tuned better. At least the 2023 G14 works reasonably well under linux this way, though I'm thinking of going through the ACPI and fixing some of that...