here is a close up in the middle of the lighter section

Do you mind taking another close up picture on a cloudy day or after the sun is off the area. If you can get much closer to see if there are any spots on the dead grass blades it would help.

Was there any delay in putting the sod down? Like did the sod sit on the pallet for a day or two before putting it down? That can lead to disease right on the pallet, and it does not go away automatically.

I have always had excellent luck using (believe it or not) ordinary corn meal on fungal disease in St Augustine. Get it in bulk at a feed store. 50 pounds should cost around $20 these days. Apply at a rate of 20 pounds per 1,000 square feet and reapply in 3 weeks. Apply to the entire lawn because corn meal is an organic fertilizer that will turn the grass dark green where it goes. If you don't cover the entire lawn you will have new dark green patches instead of yellow patches.

There is another product which sounds like corn meal but is not what you want. That product is corn gluten meal. What you want is ordinary corn meal.

How often do you water and for how long? Is there any chance you have standing water in those places?

I was watering twice per week for 35 min in each zone. I am switching to once per week after doing some reading and will do a deeper water time, just not sure how long yet.
I am positive there is no standing water in this area of the lawn.
I do not believe there was any delay in the laying the sod but I was not present to see if it actually sat on the pallet before laying, so I can't say for sure.
I took some more close up photos, I hope you can see it better.
I am willing to try the corn meal but I was hoping to figure out what the cause was first. are you thinking fungal?
thanks for the response I appreciate it

close up 2, you can see some spots in upper left area of picture. but most of the blades of grass are just a lighter color in general

close up 3

Definitely fungal. See the yellow blades in the lower right corner in pic #1? Those have spots that shout, "fungal." You can barely see it in the brown blades, too. Excellent photos. Thanks.

The beauty of ordinary corn meal is that it works biologically against several disease processes. You don't have to diagnose it. Just use it.

Corn meal works by attracting a predatory fungus called trichoderma (try koh DER mah). The first fungal species which decompose the corn attract the trichoderma which grows in population. Once the trichoderma feeds off of the previous fungi in the food chain, that large population of trichoderma goes after the disease fungi causing your problem. This is a biological process so it can take 3 full weeks to see results. Then if you reapply the corn on top of the already high population of trichoderma, you get a bonus dose of trichoderma to take out anything the first dose missed. And I believe I mentioned that corn is an organic fertilizer. It should thicken the grass and green it up while making it grow just slightly faster.

Also if you are not mower's highest setting, you can change that now.

thank you!
should I be concerned with corn meal taking 3 full weeks to work? how long does it take a fungus like this to kill the grass to the point it will not make a comeback?