This is indeed my first time with Pi-hole. But I have some experience with Ubuntu from programming.
I know that it seems like I'm trying a lot of things at the same time but the problem started when I followed a simple tutorial.
The time synchronization problem has been an issue since the beginning.
I tried a lot of different things to fix the issue before posting on a forum because a lot of times there are already solutions elsewhere but I was unable to solve my problem.
This afternoon I freshly installed Rasbian on my pi to make sure I restarted on a clean slate and worked slowly to make sure everything worked along the way. Time synchronization and Unbound worked fine until I rebooted my pi after installing Pi-hole.
Without Unbound my Pi-hole didn't work as well, so that doesn't seem to be causing it.
Before using Chrony I didn't change any time-related settings and got the same results.