This looks like heat creep and/or clog. Check the hotend fan (not the part cooling one). If it starts happening after a while, it’s either that or the nozzle has cooled too much. But if it happens with lower speed as well, then I wouldn’t say it’s that it’s the latter. Try increasing the temperature. I’m printing mine at 270°C. Also I keep the bed at 70°C but that’s not important. I’ve had issues like that with bad conducting nozzles (hardened/stainless steel) and thermistors not properly seated on the heat block. When this happens, pause the print, try feeding the filament by hand and see if there is any resistance (can you feel the clog). Try increasing the temperature, reduce the retraction distance to try and avoid it. I’m printing exclusively with petg for years now, never had issues like this due to moisture. You get more stringing, yes, but no failures on actual printing.
Are they any close? Seems like they’ve been doing it for ages and they aren’t close.