Just to illustrate my point above, here is a graph of a test I did on a few phone chargers and the current official Pi 4 PSU:
These measurements were taken with a small dummy load with voltage read at the plug, so what the Pi would see and therefore includes any cable losses.
The official Pi PSU output is specified at 5.1V 3.0A. It maintains above 5V until the load reaches 2.25A, and the voltage recorded at its rated output was 4.91V.
The Xiaomi charger has a specified output of 5.0V 2.0A. It drops below 5V almost as soon as any load is put on it. At 1A it’s still supplying 4.97V however and at its rated output it’s supplying 4.87V. It has a protection circuit that cuts the power above 2.2A. This might be OK to power a Pi 3 and dongle, but add an LNA or Pi 4 and it would be marginal.
The Asus charger is also rated at 5.0V 2.0A. I tested this with the same USB-C cable as used on the Xiaomi charger, but also with a micro USB cable. The power loss through the micro USB connector is considerable - at the 2A rated load, the micro USB was showing only 4.65V, whereas as the USB-C cable was showing 4.83V. This charger would be problematic powering a pi 3 (and this is the case, since I tested it on a pi as well) unless with an extremely good quality connector and cable.
I’ve only tested one phone charger that is up to powering a Pi 4 (an LG 3.0A USB-C one) which I don’t have detailed data for, but is currently running my ADS-B pi.
Considering the low cost, getting the official power supply would seem to be very worthwhile, immediately eliminating a common cause of stability problems.