Recently, I started experimenting with new filaments on my Ender 3 V2. I got a spool from here.
This is PETG filament and I started dialing in the temperature to run a smooth print. I found on my V2, if I run the filament around 240 °C, it prints very smoothly and the extruder doesn't jitter or distort the filament during printing.
However, I found after the printer was printing for about an hour it had reduced its hotend temperature to 210 °C and the print went bad! I have a stock hotend for the V2. Any thoughts as to why the temperature would have reduced itself?