Maybe I'm missing something, but where/how does the power source 12v lead connect?
And what does the step-down from 12 to 5v? I hope it isn't a couple diodes & resistors in the USB A end. Don't see anything about load rating.
No affiliation, just a quick Google search, but I'm inclined to use something like this.
Separate power convertor, regulation and max load specs. And less than half the price.
https://konnected.io/products/12v-to-5v-usb...nt=828080488468