The Stallman-era idea of taking possession of your own copy of open source code so that you can do with you want with it, is now being argued to be too dangerous for you.
You should just trust the upstream team, just like you would with proprietary software, and if you reaaally need something custom, you should let them take a look at your idea in a PR and they’ll decide if it’s a good idea that can be merged when they’re ready to schedule it in.
When you look at the security risks and developer talent at play today, you can understand why this argument makes some sense. But if you’ve watched or been part of the of the Open Source Revolution, you kinda have to laugh at the irony.