Looks like it hit your fender or a rock and got sliced. Nothing to worry about, not deep at all. If it's your fender though it would be a good idea to solve the issue before it cuts it worse.
This is a rear tire, stock size. No chance this this from hitting the fender.
These marks are on every lug of this tire, not just this one section.
It hit something, it's not a tire issue, it was caused by something you did even if you don't know you did it. Stock size tire, is it on a stock rim? Do you wheel it or only street driven?
Do you do a lot of gravel/shale driving?
I see a lot of that from my customers who do a lot of gravel driving.Mostly that in Colorado.