You might want to look into ColorBond paint for such minor wear such as ColorBond (159) GM Very Dk Pewter LVP Leather, Vinyl & Hard Plastic Refinisher Spray Paint; find your own actual interior color name through the production code tag. (I should mention that there have been complaints of clogged cans received that are probably due to less-than-frequent product movement). I haven't tried it myself only because my past refurbishing is still passable (and I forgot I wanted to do this). Judging by the picture, I would spray some paint in a container and dab it along the worn edge. Don't let "spray paint cans" turn you off for leather (which that part may be a mixture of material anyway, e.g. Pleather©). Effective and economical restoration can be achieved over what leather repair people tell you must be done, is impossible or imply as ridiculous methods - they'll have you going back to the tanning process, and then say "It will never match".
Also, you might want to watch this: https://youtu.be/rq2k9HwjSpY
- This, what appears to be a car restorer (for resale) and YouTube video maker, has some impressive looking restorations (at least in the video as opposed to real-life). Judging by this, his other videos and commenter replies, I have trust and confidence in the level and degree of his fix-up work/methods.
You might also look for shoe/boot polish or sole dye that will put on enough color to make it contrast less. I would even go as far as using a magic-marker if I found the right color.
Hope this helps/ meets your standard.