Dear Kappy,
I have tried all 11 options what you have recommended step by step. Furthermore, I have tried to get back to Mojave by creating an external flash booting and installing card.
I have deleted all possible saved data on HDD of my MacBook Pro 2015.
It helps first 20 minutes and USB increases the power to my iPhone XR to 1600 mah (I think indicating correctly). After 20 minutes it again crushes down to 500mah and again starts connecting and disconnecting every second.
I suppose, that this controller is a software bug implemented with 2100mah on saving mode to charge the iPhones and working incorrectly.
I would like to ask if there is a possibility to try TOTAL go to DEFAULT status, when none of the settings saved on the "background" chips, settings, bios and do complete RESET of the computer and start from absolutely BLANK Hardware to install macOS Catalina and see what happens? I mean NVRAM, SMC and there might be more something that not known for me. New OS can set on its own vision and fix it to normal settings that it should be. I am not sure if it will fix the problem, as I think this is a software bug from the developers and should be fixed by programmers, but not bad to give it a try.
Thank you very much. I really need to fix this issue.
Kindly yours,
Atabek