I find it very hard to believe that Apple is going to delay only one of the pro models. It makes no sense to me, so until they make that announcement tomorrow I’m going to assume that the pro models will release the same day.
Maybe because this year Pro Max has newer 6.7 inch display which suppliers has tough time producing it. iPhone 12 mini which also has newer 5.4 inch display will be released in Novemeber as per leaks. Other screen sizes like 5.8 inch and 6.1 inch were released before so probably they are easier to make.