Thanks Guys for all answers.
Yes, I have Tahoe 24gl diesel.
I’m using it for the long trips not at all in the city.
And after some research I found, GM released another update in Feb 2023 that changed the previous vehicle parameters.
After another trip I found my mpg get much better than before.
I believe after every update, the vehicle will start to learn the driving parameter and adjust the mpg based on how you drive your vehicle.