Rpi 4 specifies 5.1V 3A PSU. This is 15.3W ability not fully used. At least not all of the time or without heavy peripherals.*
Your Fluke meter shouldn't have gone off scale in Ampere series measuring mode. Maybe there is a shorted or reversed end plug/cable?
Dummy tests for this kind of rail & load range take three 4.7Ω/10W resistors. One pulls 5.1V/4.7Ω=1.085A. Paralleling a second one pulls 2.17A. Paralleling a third one pulls 3.255A.
Those tests aren't sustainable with small on board Q2 heatsink for long. Short time tests only. But if passed without considerable rail dropping and LEDs not extinguishing it means there's no problem with your PSU configuration & parts even for 3A peaks and bit more.
*RPi Power Benchmarks
Your Fluke meter shouldn't have gone off scale in Ampere series measuring mode. Maybe there is a shorted or reversed end plug/cable?
Dummy tests for this kind of rail & load range take three 4.7Ω/10W resistors. One pulls 5.1V/4.7Ω=1.085A. Paralleling a second one pulls 2.17A. Paralleling a third one pulls 3.255A.
Those tests aren't sustainable with small on board Q2 heatsink for long. Short time tests only. But if passed without considerable rail dropping and LEDs not extinguishing it means there's no problem with your PSU configuration & parts even for 3A peaks and bit more.
*RPi Power Benchmarks