bell curve pot???

https://preview.redd.it/vuyop9w05zbh1.png?width=915&format=png&auto=webp&s=06d37231e58075bdf6c71cf424c5570983906cc2

My fiance's guitar sometimes cut out and she asked me to take a look at it, i took readings from the tone control, a new linear pot and the volume pot... which somehow is a bell curve? I've done some looking and can't figure it out. Is it just broken? my gut would say it is, but whys is it such a perfect curve??? im so lost