A clog, over extrusion or temp to high? Printing on a Prusa i3 pro b with temps at 210/50
Is that 3mm filament?
looking at the deformation, looks like heat creeped up the inside printhead channel and expanded the filament inside. Not enough flow or too much heat will cause that. 3mm filament was bad for that, its why is gone out of style.
It’s made by 3d Solutech but now that I think about it, I have had probs the last two times I’ve purchased this brand as well
Using 3mm filament for over 5 years now, this heat creep usually happens on poor hotends designs. I suggest replacing with a v6 or at least having a teflon tube all down the barrel. Otherwise you can only print with no or minimum retraction, low temperature as possible and fast extruding. Keep the fan on the hotend always on and good luck
This looks like too much heat getting past the heat-break. Like Zohar says, keep the heat sink fan on all the time, and put a layer of kapton tape around your heat block.