Joe Rossignol, MacRumors:

Last month, FCC filings revealed that Apple Watch Series 7 models are equipped with a new module that enables 60.5GHz wireless data transfer. This module is not advertised on Apple’s website and is likely for Apple’s internal use only.

And:

It’s also worth noting that Series 7 models feature IP6X-rated dust resistance, so perhaps the diagnostic port’s removal helped with that to some degree.

Interesting. Surprised that Apple would get rid of that port. A sign that they might be willing to remove other ports?