Since my laptop charges with USB C, so when the standard charger broke, I used the USB from an EcoFlow battery, and the display on the battery said the laptop pulled 25-30 watts while charging. So, why can’t I use just any USB brick that can output more than 30 watts? Is there something that is bound to go wrong that I don’t know about? Are laptop chargers really that special?
It depends. Some laptops won’t switch on their full cpu/gpu if they aren’t connected to enough power.
My Lenovo for instance will switch to a high refresh rate when using its native power supply.