I have a Sapphire Plus printer which I have heavily modified (out of the box it is a piece of junk). After finally changing the mainboard and installing Klipper I got it to print reliably. Of course the next thing I wanted to do was print fast. It quickly became apparent that the E3D V6 hotend and the anemic 3010 fans severely limited said goal. So I got myself a Dragon HF hotend, a 5020 blower and printed this print head. From the get go I had massive problems with retraction, even after calibrating pressure advance the retraction towers I tried in Orca Slicer where all stringy messes. I kinda got it under control by severely slowing the retraction speed to 25mm/s with a 0.4mm retraction distance with nozzle wipe.
But now I'm sometimes getting these weird stringing artifacts on prints. Not on every print and not on every part, it's just certain seams that get them. I'm currently printing with a 0.6mm CHT nozzle and a fresh roll of Elegoo PLA. Does anyone have any idea what could be the culprit? It ruined the finish on a few otherwise perfect prints.
I even tried out this print: 
since it has a lot of retractions, but of course that one turned out perfectly apart from a few tiny whisps.
This can happen with under extrusion or over extrusion. You can try the auto towers plugin on Cura and print some Retraction Towers.
Already ran through all the flow rate, pressure advance, retraction towers and maximum flow rate calibrations in Orca Slicer