@rinart73
For me works very nice.
Make sure you did a complete unroot before !!!
Then flash magisk -> phh superuser -> install magisk manager app // (or try to install the app first)
If phh super user doesn´t ask for root rights for the manager reboot.
Allow root right always for magisk manager.
Reboot.
Go into the magisk manager -> magisk hide and add pokemon go.
Reboot.
Now it should work.
(Normally you don´t have to reboot as often but maybe it helps.)
Do that step by step and it should work.
If it doesn´t you made a mistake, maybe no complete unroot. Try after the unroot if Pokemon Go works.
If you think you did everything correct and it still doesn´t work, then ask in the magisk thread guys (can´t tell more as i did).