Reading all the wifi issues, it makes me wonder whether this is really a HW / Material or a SW thing. For all we know the only thing that should be 100% same is the material, in this case Titanium. SW not so much, as even the SW package (iOS) is the same for the 15 PROs, the users wifi home configuration (QoS f.e.), installed application using wifi on background, modem or router firmware update, may cause the wifi performance degradation. Or maybe the early 15pro got a different wifi module, which has been later identified as faulty or worse in some way idk.
It would be interesting to see a poll of iPhone 15 PRO users who have / have not wifi issues..Maybe it is a relatively small group affected by this problem. Not saying insignificant, but relative small to the total number of sold 15pros.