Xbox Game Pass Ultimate - XCloud using low connection speed

Hello, everyone!

I'm trying xcloud for mobile now for it seems an amazing option for playing good games for a nicier price. However in my country (Brazil) there is no xcloud server so that I have to use an US VPN. Actually my VPN service is great and my tests show that I
can achieve uptime to 5.3 Megabytes/s of download, which should be enough to run cloud gaming. YouTube and Netflix indeed achieve high velocities with VPN turned on.

Nevertheless Game Pass app only uses up to 100 kb/s of my connection, which is pretty weird to me. That causes some considerable pixelated gameplay experiences, mainly in games in which the scenario changes with frequency like open world games. So far I've
tested on Gears of War 5, Hellblade: Senuas's Sacrifice, and The Witcher 3, of which the last one is the worse.

I've tried some solutions from the online support, but they didn't approach my specific problem with Game Pass app. Do you know why is Game Pass consuming a lower speed of my connection, since there is no problem with VPN, and how to fix it?

:)