It looks to me like the signal wire for motor 1 and 4 are going to motor 4 based on the betaflight diagram
Motors are numbered as follows in the diagram:
one is front left motor
two is front right
three is back right
four is back left.
So couple of problems, the sliders aren't controlling the right motors and looks like a couple of signal wires might be shorted or again some misconfig in the MCU on the FC for the motor outputs... essentially if some resource mapping is wrong you can either fix it by swapping around signal wires or can figure out what resources are currently used (which pins on MCU go to what pad/hole on the FC). First suggestion would be to flash the firmware and make sure you have the correct target selected when downloading/flashing the firmware and allow betaflight to apply any config after initial flash/reboot before doing more setup (reboot it a few times manually if need be but should see betaflight ask to apply config).
Yah honestly have barely dug into the code despite somewhat understanding some of it . I just happened to also have this problem before where I burnt off one of my motor pads and had to get one of the other outputs to act as a motor output so lesson learned the hard way on how to get resource mapping to work.
If you jump into the CLI mode of betaflight configurator app and type "help" or "diff" or "resource(s)" can sort of glean a fair amount of info from all the parameters that are setup in the firmware that get shown there, basically configurator is just a graphical interface for setting all the parameters you can see listed out there and there's even more you can tweak from the CLI mode. Mostly built up some knowledge in this arena watching JB vids and googling and ending up on Oscar Liang's site.