It's not the tip what rises, it's the ambient temperature sensor.
It goes from 25ºC to 36ºC,
seems it's disabling the external NTC for some reason, using the stm32 temperature instead.When the handle or tip is removed, the internal sensor is never used, unless the NTC is disabled in the menu.
That can be quickly checked out, remove the handle connector, the ambient should show -99.9ºC.
If it doesn't, the NTC is disabled. In that case the value should never change, regardless if the handle is connected or not.
Check your wiring. I can get similar results when I connect the handle only partially from one side, changes between 13 and 25ºC.
In your case, it seems like it isn't making a good ground connection, and travels back through the shake circuitry.
I checked the code and didn't find anything. Last weeks were minor updates, mainly to the user interface, translations, nothing to the sensors.
If you keep thinking it's a firmware thing, go to
Github history and start trying builds, from newer to older.
Ensure it's not the wiring, test it thoroughly!
Is anyone else able to replicate that issue?