M4 - 3 USB-C
M4 Pro - 5 USB-C
Well, the Amazon leak confirms that at least one model is going to have two front USB-C ports of some flavour.
Seems a bit silly to "waste" a USB4 controller on the M4 - considering the new iMac has the full 4 TB4 ports on the 10 core models. Esp. as the Mini is going to have at least one display permanently connected - most likely via TB4 - so there's
more reason to give it the full compliment. But, then, Apple would like you to get the M4 Pro... and leaving off a TB4 port saves them an Intel TB re-timer chip.
Again, looking at the M4 iMac, the cheapest (8 core) version still only has two ports (and more limited display support) so there
could be 3 and 5 port versions of the M4 Mini - with the 5th port being USB 3.2 only.
There's also precedent for having a mix of TB4 and USB-C only ports - the M1/M3 iMac and the M1/M2 Max Studio - the SoCs appear to have some I/O lines in addition to the USB4 controller..
Here's a wild mad guess:
M4 base model: 3 rear "TB/USB4" ports
M4 "better" model: 3 rear TB4 ports, 2 front USB-C 3.2 ports (or maybe 1 USB-C 3.2, 1 TB4)
M4 Pro model: 3 rear TB4 ports - 2 front ports, USB-C 3.2 or TB4 mix depending on how many controllers the M4 Pro has.