I've never thought about an infestation but I did look up grubs and 2 things I notice.
The affected area looks similar to infested areas
I've never given it much thought, but my dog's pool many times has those grub-looking worms. He poops in a different, healthy part of the lawn. I never gave it much thought to that because I just assumed some bug comes along and lays larva in the poop and no big deal, I just pick it up. Coincidence?
I'm in Phoenix. Its been years since my grass was put it, but it was a hybrid bermuda.... tifway sounds familiar. There are definitely dog urine damages from the winter Rye. I gave up on the rye this past winter but I was still watering here and there so the dead area seemed a bit extreme for the rye to burn out like that, especially since it didn't in other areas. It just became a dull green in other areas.