PTFE pulled into extruder gears
You are probably right, I have a Tarantula as well, and this happened many times to me. The reason is mostly because the hotend fan gets too hot, stops working, then, the filament in the aluminium heat sink melts and sticks the filament inside the PTFE tube. Then, on the retraction, the PTFE is pulled into the gears just like on your picture. Also, the filament stops getting extruded a few moments later.

One solution for that was to buy a new PTFE tube with a pneumatic connector that doesn't allow it to slide into the gears. However, the diameter of the screw thread (of the one that I bought) was too large, so I had to design a new static block for the extruder to fit it. 

I chose this type of 1mm PTFE teflon tubing from aliexpress for my replacement.

Maybe you can find a pneumatic connector with the proper diameter.

However the real solution is to check why the heat sink is getting too hot. I bought a few other fans and printed an additional support for them on the hotend and I am making sure the fan stays on all the time.

I hope it helps!