[0x38B]

In case you still use the keyboard, you may be able to solve the wakeup issue by preventing the wakeup in /proc/acpi/wakeup - see (1). When I used a Surface Go 2, this was how I prevented the keyboard case from waking it up and draining the battery.

1: https://ubuntu-mate.community/t/power-management-acpi-wake-u...

[jwatt]

As it happens, a kernel update appears to have fixed the issue, but thank you for this tip.