Bugs that hide other bugs
When you have bugs that block access to sections of your software, other bugs start to accumulate there.
This often happens with projects in development where it’s more acceptable to say, “This is broken right now”. The trouble is that while that area is inaccessible, nobody can fix the known bugs in it. New ones will crop up from things like external API changes or refactoring of other systems.
Knowing when a bug started occurring can be a crucial piece of data, so when an area of your codebase is inaccessible due to some other bug, the new ones don’t have a “birth date”. This makes them harder to fix than necessary.
These kinds of bugs should be prioritized to minimize bug accumulation.