Speccy counts 5 pci slots but I know I only have 4, where is the 5th?
Speccy has not had a functional update since May 2018 - 6 years ago now.
As it's 6-years old then unless/until it does get updated it is going to continue to report newer chipsets and other newer hardware incorrectly.
When, or even IF, any future update to Speccy may happen is anyones guess at this time.
It doesn't make much money, so I assume that it it is not a priority to develop.
If that would've been a laptop mobo I would've guessed either a socketed or soldered on Wi-Fi card, but with a desktop no.