To some degree this is unavoidable, though, excessive grinding of filament will add to this, caused by either a blocked hot end, insufficiant heating etc. Basicly filament is being fed faster than it can extrude.
Yours looks like a CR10 (s Pro V2?) feed or similar. A few crumbs should not be a problem.
Also make sure the filament is feeding in straight, though this would leave residue around or below the entrace of the feeder (before the bowden tube and wheels. Far left of your picture.
I upgraded my bowden set up to a direct feed Sprite extruder. Much easier to run and maintain!
Tension might be a little too tight?
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Not sure where the setting is these days but reducing the maximum number of retractions also helps, minimises the number of times the extruder winds the filament in/out in the same place.