bcachefs was always a module. You don’t want it in your kennel if you are not using it. The difference is that it used to ship in the mainline source code and be built as a module that was already built and on your drive.

If you build bcachefs as a module yourself (via DMKS or directly), it works the same as if you got it with your distro.

If you use bcachefs as root, the danger is booting with a kernel that lacks the module.

I hate that bcachefs is not in the kernel, and my primary distro does not use DKMS. But, if you can get a module built, there is no loss of functionality or performance.