Poor performance using external power bank on my 5420

Ive been using a USB C powerbank as a way to double my battery.  Its only 18w but watching youtube videos im only using 12w so it never goes into my laptops battery until the USB bank is spent.  Very convenient thanks to USB C but a recent update, im not sure if it was a firmware or windows update, using the USB C really makes everything 2x slower for some reason, especially youtube videso which is a bummer. Now i cant use this battery bank anymore to double my capacity since it ruines the performance.  But it wasnt doing this before. why?  Do i have to upgrade to linux?  Im getting tired of these constant changes , i liked the system the way it was last month, all these new updates just change things that arent for the better in my experience.  Is this ia  bug? Or a  new feature no one thought the consequences of?