I’ll check to see if my settings were saved over WiFi. I can’t see a reason why they wouldn’t unless Luban, or the snapmaker flavour of Marllin, is specifically coded to prevent it. For some reason, Luban does not appear to be coded to display the controllers response over WiFi, or perhaps the controller has been coded not to send it, I don’t know.
The Snapmaker 2.0 hotend does not have a PTFE tube in it, it’s all stainless steel. I do agree, however, that the pressure induced by the hotend could change the extruder calibration. Different filament types, different manufacturers, even different colours will also have an effect. Even without the hotend in place, the factory extruder calibration will cause AT LEAST 10% or so underextrusion. Putting the hotend in can make it worse.
The upshot is, as has been mentioned all over the internet for the past decade or so, you really need to run some calibration for each different filament type that you use.