<p>While printing a <a href="https://www.thingiverse.com/thing:3932302" rel="nofollow noreferrer">paint rack from thingiverse</a> I keep getting jams. Other prints (shorter) work fine. Can anyone give me a clue?</p>
<p>Here's a <a href="https://photos.app.goo.gl/PQuJwqNdYWSMTiwm6" rel="nofollow noreferrer">video of the printer</a></p>
<p>I thought it was heat creep so I increased the speed and decreased the hot end temperature. It generally prints for several hours then jams.</p>

When I started printing ABS with my Prusa i3 MK3 MMU2+ printer, I started experiencing jams on some longer prints, which was heat creap, possibly combined with old filament.
I improved the cooling by filling the gap between the sides of the heat sink and the plastic extruder body. I think I stuffed it with some soft foam rubber, but anything that can handle the (what should be fairly cool) temperature should work.
My hypothesis is that with gap allowed too much of the air to pass without engaging the heat sink, compromising the cooling.
With that change, I haven't had heat-creap jams.
You aren't printing ABS, but the temperature is high, and PLA softens as a low temperature. IMO, it would still be worth making the change.
It is the gap on the front and rear sides that I blocked.  The heatsink fins are fully open for air flow.
Some people here have changed out the Noctua fan for one that is noisier and pushes more air, which should also work. I appreciate the quiet fan, so I tried to get more work out of the fan I had.