FWIW, seems they tweaked the wi-fi band preference in Beta 2. I have a single SSID with both 2.4 and 5Ghz bands, and after the update, my XS clearly prefers the 5Ghz band. In Beta 1, it would only hop on the 5Ghz band if I was lucky (e.g. 1 out of 10 times maybe).
Would be curious if you xs continues to hold onto the 5ghz band. I too have an xs and are experiencing the connectivity issue of the xs preferring the 2.4ghz band. Been working with apple engineers and sending in diagnostic logs as well as others on these forums. Hoping this is a fix!