I think there are 2 types of fork in my understanding. It can be a good or a bad thing. You should be looking for the reason for doing it. If it's really good for the project
A fork is decision about how to move forward with a software project. The fork can make some things that used to be permissionable invalid and things that were invalid are now considered valid. This decision can be a good idea or a bad idea - but that's different. In general forks arrive when two sets of people disagree on the correct action. The solution is to take both actions.
It gets more involved than this - but this is a common issue in the software development world.