Why did my PLA crumble after 6 weeks idle in my printer?

I left a spool of eSun PLA+ beige in my Prusa MK4 with Prusa enclosure, which has sat idle since my last print about 6 weeks ago. The enclosure has a PTFE filament feed tube that runs the filament from the spool to the extruder.

Today I went to change the filament, and it broke apart in several pieces, right at the ends of the ptfe filament feed tube. The filament on the spool itself - within an inch of where it simply separated from the broken bits - I can fold over 180° tight without breaking it. Even the several ~1" lengths of broken bits are similarly ductile.

Ambient humidity is something like 15% (per my filament dryer) to 30% (per my dehumidifier, which is idle because it's winter).

Any idea why this happened? I'm curious about maybe interactions with the PETG parts that the broken pieces were close to (that's the only thing I can come up with, anyway).