I had a set of cheapish (not the cheapest) Canadian tire house brand tires, that had similar indentations. They never had an issue with the indentations for the few years I ran them, just wet traction became atrocious.
The Senior Tech at the shop where I bought the tires said it was just the ply in the rubber and it was nothing to be concerned about. He explained that in the factory when the rubber is being cut that it will sometimes be cut in a manner where the 4-ply section ends up being predominantly exposed the way it did on my tires. He said Hankook “entry” level tires like I have are gonna show like that.
All in all, he nor the service writer tried to sell me new tires and said it was not an issue just as a previous poster had said as well.