I was curious so I tried to register with a Proton Pass liss which is @passmail.net and they also refuse those. I think they are afraid of services which allow to easily create multiple aliases, because people could create multiple accounts very easily (scammers maybe)? It’s a dumb rationale because it’s not much harder to create many Gmail accounts but that’s the only reason I can think of.

Usually only one axis skips steps, especially since the MK4 has collision detection. A shift in both axes would rather indicate a steel sheet shift imo

Did you losen the idler tension screws? TPE requires that the tension is very very light otherwise it tends to buckle around the gear before entering the nozzle tube. Reducing retractions to a minimum is also always a good idea, as well as limiting the max flow rate.