they force USB2.0 speeds (same as lightning) unless you get the Pro (this is unverified)

Not as much force, it’s just the chip in there isn’t good.

It’s very verified by the way, it’s in the Tech Specs.

IPhone 15: usb 2 to 480 Mbps (source)
IPhone 15 Pro: usb 3 up to 10 Gbps (source)