I don't think that it is the cameras. The film overexposes to the same extent with three different camera - F1n, AE-1, A-1. I am totally convinced that the film emulsion has changed and does not have the same response in bright light situations. Provia users beware of bright lite situations, and decrease exposure by 1/3 - 1/2 stop.
Post some examples.
I've been shooting provia for 12+ years with emulsions dating back to the early 90's and I haven't had this issue you speak of. I also use a spot meter.