There's no "magic" involved in charging.
The standard Apple charger delivers the same voltage and amps to the laptop when used on a 120V grid as when used on a 230V grid. So the type of grid should not matter.
20A fuses are definitely not common in all of the EU, it is much more common to have 10A fuses for lights and other outlets in normal homes, and ...
Apple publishes technical specifications for its products and are available at its website.
Have a look at: MacBook Air (13-inch, 2017) - Technical Specifications
Under Battery and Power2 it shows:
45W MagSafe 2 Power Adapter with cable management; MagSafe 2 power port
As your power bank only has an output of 5V/2.4A, which would be 12 watts, it's little ...
You may or may not get any useful information from pmset, but it takes virtually no effort, so why not?
What is pmset? A command line utility for manipulating and viewing power management setttings under macos. Ref Wikipedia article
You can access pmset from a terminal window. You can access the system manual for pmset by entering man pmset at the ...
Try to do a SMC and PRAM reset.
SMC, amongst others, controls power management of your Mac. From https://support.apple.com/en-us/HT201295:
These symptoms might mean that an SMC reset is necessary:
The battery doesn't charge properly.
Do you have or can you download iStat Menus; then look at the DC In sensor with both adapters connected. I suspect the MagSafe connector on your Mac has detritus in it and needs to be cleaned.
Check how many watts of input are being provided with each adapter. The LED may not be changing because it can't transfer the expected amount of current and/or the ...
I have no clue about the Xiaomi, but I charge my power bank while charging my 15" MacBook Pro all the time...
Actually, I generally have my power bank charging my iPad Pro and my Apple Watch Valet, which is charging my iPhone and Apple Watch.