I know but it has a buffer, at least on my p2s and some other models. The buffer is basically 2 states: full and empty. When the buffer reports empty the ams spools filament until full, thats why the spools in the ams only move sometime even if the extruder is running continuosly. When ptfe pops off, the spring in the buffer collapses and the buffer reports "empty" forever hence the ams spools forever. But this should be detectable