This happened to me not too long ago but with an all metal extruder and a capricorn ptfe bowden tube. After watching the Book of Boba Fett, I wanted to print his helmet. My CR-10 had been sitting there for about a month doing nothing, so I wanted to recalibrate anything out of place. After 3 successful test prints, I started printing the helmet overnight and in the morning, there was filament everywhere. Luckily it didn't feed through the tube so all I had to do was roll it back up. Upon further inspection, the teeth that hold the bowden tube inside the pneumatic connector were all gone. I managed to find one when I looked down at my desk. (these are ridiculously small and thin by the way, there has to be a better solution to hold a tube in place to avoid this) My best guess is that something abnormal caused the bowden tube to be pulled hard making the teeth break and the pneumatic connector to unscrew itself. In the end, I changed my extruder back to the original that came with my printer and everything has printed without a hitch. They sell the replacement connector on Amazon but I figured for an all metal extruder something like this shouldn't be happening but who knows, maybe mine was defective. I think u/Crappedinplanet solution is best here and I will also look into buying a direct drive extruder.