No idea what the deal is here.
This is on my slightly modded Creality Ender 3 Pro. (It's got a CR-Touch, better springs, a metal extruder assembly, an upgraded official Ender 3 Pro motherboard with quieter stepper controller capability. Nothing all that invasive.) Identical gcode worked perfectly fine on my Ender 3 V2 Neo. (Which is sufficiently similar that gcode is interchangeable.) I've used that particular roll of filament for other prints before and had no issues. And the same printer has given me no other similar issues with other prints, including prints that were taller than where it failed on these photographed prints.
After the one on the right failed, I assumed it was a clog and did a cold pull. The second print (still on the bed) started out just fine, but started underextruding the same way at almost exactly the same place. I say "almost" because looking closely in person, it does look like the second started underextruding just maybe 3 to 4 layers later than the first.
I suppose it's possible it was a second clog at almost exactly the same place on the second print, but it's pretty coincidental if so. Plus recovering spontaneously on that second print is pretty weird.
I dunno. Just very weird and I'm hoping folks here have an idea what I might look into to find a solution. Thanks in advance!
Also, just a few more images in case it helps:
It's definitely being under extruded. As to what's causing that, my first guess would have been a clogged nozzle... but if it's happening not-at-random, it's probably not that.
is there a way to see a log of hot end temps across the prior prints? it could be that something is causing the the machine to speed up putting out more plastic and the hot end struggling to keep up, though I'm just spitballing here.