I was told to make a separated about this issue so here it is.
I am having issues when booting my 4B when all four USB ports are populated.
Some quick background on my setup. My Power supply is a 5V 3A supply. I have a single arduino uno being powered by the pi. I have 3 USB2.0 cameras attached. The cameras have been spliced so that only data cables are going into the power. The 5V for the cameras are being powered by a separate power supply. I am only using VNC to view which means I don't see anything while booting.
While booting the pi only has the red light on, no green ACK light. When I unplug 2 of the three cameras (randomly selected), the ACK light comes on and I immediately plug back the other cameras back in and it boots fine from there. This happens while turning on the unit or restarting the unit.
Any ideas why this would happen? The cameras and the arduino work work fine after the pi is booted.