Hi,

Yellowing in pin oaks is usually caused by iron chlorosis.  The underlying cause is too high a pH level in your soil which makes it hard for the tree to take up iron.  I'm sending you a link to a great article about this which explains what iron chlorosis looks like, what it is and how to treat it.  A few of the treatments require an arborist so be sure to get a "real" (licensed) arborist.  It might also be good to get your soil tested around your tree to see if the soil is alkaline.  Some areas of the state are more alkaline than others; I don't know where you are.  If you need information about hiring an arborist or getting your soil tested, let me know.  Let me know if you have any more questions,

Barb

https://www.canr.msu.edu/news/severe_chlorosis_in_pin_oaks#:~:text=Chlorosis%20in%20pin%20oaks%20is,pH%20%E2%80%93%20pH%20greater%20than%207.

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You're welcome.  Good luck.