I am using the Ender3-v4.2.7-Stock-20210711.bin firmware and I there is a problem with the filament load option. It loads the filament too fast, making it stuck in the hotend and the gears of the extruder wear the filament out, leaving debris and losing the grip of it.
Is it really a bug? Is it possible to change the loading speed in the config panel?
There’s a number of factors here. It might be worth a video of your issue.
The length of the bowden can be changed in configuration - and should match the length of the bowden + feed in into the hotend. The length of the fast load / unload function can be set with the M603 command.
On a load, the printer will fast-load the amount of filament as configured in M603, perform a slow purge of 10mm, and then prompt if you want to purge more or continue.
It may well be likely that if you have a shorter bowden length, it is set too long within the M603 configuration.