What does ChatGPT have to do with this…? This is what FP themselves say https://support.fairphone.com/hc/en-us/articles/9836188988049-Audio-Jack-3-5mm

I have a FP3 with a jack, for reference. It doesn’t have an IP rating. FP4 has IP54, FP5/6 both have IP55. Also yes, phones have become bigger, but they have more stuff inside. More cameras, for example.

I mean, the jack is literally a hole in the chassis of the phone, while I cannot exclude the fact that someone managed to make a design with good IP rating, I can very easily see that it makes it much harder.