I have Ender 5 pro.
I used it without a problem for 2 years.
And then, the following 2 years prints got very bad quality. It skips half of the print areas.
I realized that during the print, extruder makes sudden backward moves (in the reverse direction).
I marked the filament.
So, overall the filament moves forward (towards the nozzle).
But because of these many reverse moves not enough filament is going to the nozzle.
As a result, the printed material has many gaps, and useless.