@droftarts thank you for the reply and sorry for the late reply.

After sending the message I continued tinkering and searching for clues of why that happened, and I've discovered what was the problem:

By using the BLV mgn profile on Cura, the special option "Set Relative Extrusion" is disabled, meaning that when I was applying the "set relative extrusion" command inside the gcode, the acual extrusion values inside the print gcode were still absolute and exponentially told the machine to extrude more and more filament, more than it could do.

By removing the relative extrusion command, the printer worked like a charm.
After that, I've tried using other slicers like Orca, and it managed to convert to relative extrusion with no problem, with also a lot more of options for me to customize. So I'll probably stick to it from now on.

That was genuinely my bad to not have thought of that before, tomorrow I'll set this post to resolved for the posterity.

@mrehorstdmd true <2mm would be massive. but that would also double the material use.
the prints im doing are just negative molds that get filled with plaster, so they just need to be stable enough to not deform under the weight of the plaster.

and yes ive also noticed that clean retractions with the bigger nozzles are hard. Specifically the de-retract. when the material rips of the from the rest of the material its just not a clean cut, so when the de-retract comes around its a bit messy. (and the z-hop doesnt help)

would be interesting to see if one could set a slicing behavior so that when the de-retract happens and the nozzle waits a tiny bit for the mess to be pressed into the below layer and only then continues its journey.

@shadowphile said in Where to start with a comprehensive extrusion calibration?:

that helps keep calibration from turning into a exercise in OCD behavior

That's a good observation. At some point we also need to recognize the FDM in general has limitations when it comes to print quality. Similar to the situation with dot matrix printers in the early days of desktop 2D printing.