Hi there!
After extensive research I ended up buying the CP12S Power Bank by Huawei. (
https://consumer.huawei.com/en/accessories/supercharge-powerbank-40w/ )
It's a 12000mAh Power Bank capable of delivering 40W (5/9/12v at 3A).
I chose this Power Bank mainly because of its size, weight and quick recharge times. I received it completely empty and it took 2 hours to charge it to 100% (via USB-C).
I tried it with my TS80p and all I got was either constant restarts and "Low-Volt" (USB-C) or powering at 5V/3A (15W) via the USB-A port.
So I gave up on it and thought I'll just wait for a firmware fix for the TS80p.
Yesterday, I decided to try some (stiff) USB-C cables I had laying around.
I started with a cable by Choetech. (
https://www.amazon.de/gp/product/B074DTB6L3/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1 ) To my surprise, it worked perfectly!
Then I tried with another one made by ANKER. Had the same great results.
I even tried with the USB-C cable that came with my DELL Ultrasharp U4320Q and it worked perfectly.
So, as you can see, the original USB-C cable is to blame.
I'm now looking for the perfect flexible silicone USB-C cable and I'm all set!!
P.S.: My TS80p is on firmware v1.27.