Ok, udało mi się znaleźć rozwiązanie dzięki pomocy ludzi z Reddita. Wrzucam instrukcję po angielsku:
1. Download Youtube Vanced 15.05.54 (the newest), MicroG 0.2.6.17455 (the newest) and Old MicroG ( https://www.dropbox.com/s/l8xibmac3uck81d/MicroGOld.apk?dl=0 ),
2. Install new Youtube Vanced using SAI,
3. Open Youtube Vanced and put it into background,
4.Install old MicroG,
5. Go back to Youtube Vanced and log into your google account. When it gets stuck press back button/make back gesture. Your account should appear with error "check your internet connection". Put Youtube Vanced into background,
6. Install new MicroG 0.2.6.17455 WITHOUT uninstalling old MicroG.
7. Go back to Youtube Vanced!