Step one
take a closer look. A real detailed look all around the tread an inch at a time. You may find ( as I have more than once ) there’s something stuck in there…and still there. Worn off from driving to the point that it’s not obvious.
Step two
If you dont visually see something stuck in it.
Take it to the tire shop.
They’ll be able to check for bead, wheel, and valve stem leaks.
They can dismount the tire and check inside for anything stuck in the tread.