If Package A won't run on JDK 17 your entire project is stuck on JDK 11. If Package B is upgraded but has conflicts with Package A, you have to dig through old versions until you find one that works -- and you don't get upgrades.

The more games somebody has played with reflection, undocumented features, deprecations, etc. the more likely you are to have a conflict. And since package managers encourage you to depend on somebody else's code, you end up depending on everybody else's code.

The smaller and greener the project is the more likely it is you can just pull the latest versions and be happy about it. A project that was written when Java 8 was current, and continued to develop, is going to be a nightmare.