My system is a Black fw12 i5, running Windows 11. I have a USB-C power bank that supports both input and output from the USB-C port up to 18W (9V/2A) or 15W (5V/3A) depending on what the device asks for. Whenever I plug the power bank in, it insists on charging my laptop instead of letting the laptop charge it. Is there some kind of software control I can do to force the computer to charge the powerbank instead?
The easiest solution I can think of is to get a unidirectional USB C cable. I know some of the cheapest, worst quality USB C cables have (had?) this “feature” unintentionally, so surely some should be available.
What power bank are you using? Some power banks have methods to let the user manually switch between modes.
Thats very unfortunate, but I dont think there is a “simple” solution to this problem other then using a different power bank or charging it slowly with a USB A to C cable. (As in, plugging the USB A side into the framework laptop and the type C into the power bank)
Unless ofc your power bank has a second non type C charging input, in which case you could just use that.
In theory software could change the behaviour of the laptop, but the software for that is in the type c port controller, which can likely only be programmed in factory or via some test-pads on the mainboard and only communicates with the EC. There is no way for the operating system, let alone a userspace program to communicate with that at all.
It’s a one-button, 4-LED, 37Wh basic power bank that’s branded as “AT&T”.
I think it’s pretty common. All my PD compatible laptops draw electricity from the power bank. A power adapter is a source, a laptop is a sink, a power bank can be both a source and a sink, so the laptop is at the “downstream” of the power bank. If I connect both laptops with a USBC cable, the laptop with a bigger battery charges the one with a smaller battery
I always suggest getting a USB-C to USB-A adapter and then plugging a USB-A to USB-C cable to it. This way you get a directional C-to-C cable 
That’s a good idea, save for the fact that charging will then be extremely slow. None of the hardware I use supports more than 5W over USB-A; in fact my USB-A expansion cards are somehow stuck at 2.5W!