Quite frankly, this G-drive disconnecting from macOS Monterey Mac trouble happens due to unknown bugs of macOS Monterey. According to the experience of some people who also encounter this trouble, you can try an Apple-manufactured USB-C to USB-C cable to connect your G-drive and your Mac computer.
If this trouble is not fixed completely, complain to Apple tech team about the trouble that the external hard drive keeps disconnecting on Mac which runs macOS Monterey.
Take care~