I say having spent the last weekish frustrated that my printer seemed to just be awful at making prints with even loose tolerances all the sudden.
I was using filament that had been left out a month or two, so not long at all, so I thought. Killed the rest of the spool trying to tune things, prints worked perfectly when I got a new spool out.
Goddamnit.
If it makes you feel better, the very same thing happened to me a few weeks ago. Got it loaded, adjusted flow rate, temps, loaded, and the filament proceeded to crack apart. Multiple places.
Checked date, two years old. Oops.
I have filament that is now more than 5 years old and it still prints fine. But I also had 5 year old filament that printed fine at the outside of the spool, but cracked at the inner 1/3 of the spool (just a day later)