what's happening here? stringing?

[curious aardvark]

you're printing way way way way too fast and too cold and you've forgotten you have a bowden extruder.
Try 15mm/s speed and 245c temp
You can probably go up to 20mm/s
and 0.2mm layer height.

And try and keep the model on the right hand side of the bed so you don't have too extreme a bend in the bowden tube.

Ideally you want to fit a secind z-screw and convert it to a direct drive extruder.

But as it stands, you need to print really slow and hotter and avoid the left side of the print bed.

I'm impresssed it's come out as well as it has - must be pretty stiff tpu.

Yeah it's a stiffer than normal tpu.
Otherwise you'd just have had a pool of thin spaghetti on the bed :-)

The 5x faster than normal is just total nonsense.
They're claiming 150mm/s for tpu ?
In their dreams.

I have two direct drive printers both with tpu midified extrduers.
30mm/s is as fast as I print and I hate printing slow.
It's just the nature of the material.