rooting – Phone stuck in fastboot mode

I’ve rooted my OnePlus 6 yesterday. To do so, I followed this guide:

https://oneplus.gadgethacks.com/how-to/root-your-oneplus-6-with-magisk-beginners-guide-0185541/

TWRP version: 3.5.1_9-0
Magisk version: 22.0
I also installed the Magisk app on my phone

Now I’ve edited my hosts-file (needed to change some permissions to be able to modify this file
) to block some sites. I’ve restarted the phone once successfully, but now the phone will not boot anymore. When I power on, I see the OnePlus logo very briefly and then it gets stuck on the “bootloader is unlocked” warning for a long time. It then goes on into fastboot mode. If i press start from there, the process repeats. If I press recovery mode I still get into TWRP, but rebooting from there also repeats the process and does not boot up my phone succesfully.

I’m not sure, but I don’t think editing the hosts file is what caused this? Shouldn’t I be able to edit this file without bricking my device?

Any help on what happened and how I can fix this bootloop without wiping/reinstalling my entire device would be greatly appreciated; I don’t want to lose all my settings =).