Wifi is also slower, M1 Macs have only 2x2 MIMO chip (Broadcom BCM4378). In AC mode (5 GHz, HT80), it maxes with 866 Mbps link speed. Intel Macs are faster in this regard.
That said, I wouldn't necessarily expect the 16" MBP to have 3x3 either. Last time I checked, laptop oriented wifi6 3x3 chipsets didn't exist (though something may have shown up in the last few months)
Though you might have a point with 3x3 wifi6 chipsets, I didn't do any research whether there are any. Given the way the market went with wifi5 ones - with majority of vendors just using 2x2, this is something I should have expected.
I found some interesting Apple documentation on this: https://support.apple.com/en-hk/guide/deployment-reference-m...
Apple used to be one of the vendors, that bothered to put better wifi in their products than competitors; now they fell back to mediocre 2x2 that all the PC vendors use.
When transferring tens of gigabytes over network, one definitely notices when the network speed is less than what it is supposed to be.