You got lots of good advice here for sure.
I'll just want to say that I'll agree very much with @Smithy, -you sure have a "hot end cooling" issue.
Even the fact the fan is running, -does not mean your hot end cooling is good!
The heath "somehow" climb through the coupler and create high friction resulting to under extrusion..
There is also another problem, -the nozzle you're using is not in perfect match with the flat surface in the heath block to match (your latest pictures). So this match is leaking and thermoplastic is filling the threads! This cause, less thermal conductivity between nozzle and block as well as leaking filament into the coil surface.
This is information from your last pictures.
Due to this fact, your nozzle do not deliver enough heat and is leaking through the coil reducing heat transfer.
The flange between nozzle and heath block should be very "precise and even" in order to keep the temperature even through the complete heath block.
I'm using copper paste in the treads between the nozzle and the heath block. This improve the thermal contact between block and nozzle! Also it is easier to remove when needed.
It is very important to use "original nozzles" for the type of block used.
The flange between nozzle and block is very important to be correct, -not leaking here, -or else old deposit from previous print might make problem collecting up here and ruin your ongoing print.
Finally, the wires for the heath block "heating" and heath block "temperature" might cover up the inflow for the cooling radiator. This can reduce your cooling by ~35 %. "There is a small modification to improve this."
Anyway, just my opinion.