Detachable Battery on Lenovo X250 is not detected

Hello everone! I recently bought this old laptop, Lenovo X250, and it has some form of “hybrid” batteries, one internal and one detachable. It seems to be a common problem, that the detachable battery is not detected … under windows and you find a lot of solutions online for that. However, after some time of searching I do not find anything useful about this problem for any linux distro. The issue is somewhat mentioned in the Arch Wiki to this laptop, but I have no idea how that is supposed to help me.
And the detachable battery is really not detected at all, e.g. there is no BAT1 folder next to the BAT0 and AC folders. Am I right that the UEFI has something to do with that?
If you need some logs or any additional information, tell me how I can provide you with that information.
And yes, the BIOS is up to date.
I’d be glad if anyone can help.