I've noticed this.
Between an Air and a 16 Pro, same location, same carrier, same plan and prioritization, in comparing Field Test numbers, the 16 Pro has had approximately 4-5 dBm better RSRP (though quality and SNR have been a toss-up in limited comparisons, with a small edge towards the 16 Pro).
Speed test DL/UL numbers reflected the difference between the x71 and C1X modems, with the C1X more noticeably being impacted on upload.
I actually am going from the Air to the 17 Pro because of this as well as the C1X (versus Qualcomm X80) and traditional (versus plateau-surrounding) modem and antenna deployments, respectively.
Editing to add: in brief comparisons, a 17 Pro is still a couple dBm lesser-performing than the same 16 Pro mentioned. As these are all isolated, limited tests - what is everyone else seeing?