Thank you for writing.

A couple things come to mind.  

It could be a vole tunnel.  Voles typically eat their way through the grass to get to their burrows. These runways are very shallow are about two inches in diameter. Many vole holes are found underneath low lying leaves or plants, so make sure to double check near your garden or extra leafy areas.

https://extension.umn.edu/planting-and-growing-guides/vole-damage#reseeding-grass-1901261

A second possibility is a fertilizer or herbicide burn. Although, I cannot say with certainty, it looks like you are doing something close to a bluegrass monoculture lawn. These are difficult to maintain. http://ci.chanhassen.mn.us/DocumentCenter/View/4789/Choosing-Lawn-Grasses-UMN-Extension?bidId=  Chemically treated water running backwards from the sprayer down a hose and into the lawn might have created this linear wound.

I would look carefully for voles and wait. Chemical burns heal.

Feel free to write back.

Most grasses are mixed but they are mixes of several blues and a bit of rye which does not last long to give a quick greening.

Voles are detected this way (see also links above) https://www.almanac.com/pest/voles

A third possibility if grubs but I have not seen grubs do a straight line.  Take a shovel and peel off the turf at about 1.5 inches. You will see them. https://blog.davey.com/2017/07/have-japanese-beetles-check-and-control-lawn-grubs-now/#:~:text=If%20you%20see%20grubs%20in,of%20either%20diazinon%20or%20dylox