There's a thing called OpenZFS. With ZFS happened almost the same thing as with Java.
Oracle bought a company and tried to close ZFS, but people just reimplemented ZFS under a FOSS licence and community. I don't know who uses Oracle ZFS nowadays. Everyone uses OpenZFS.
It's true that there's some licence incompatibility that doesn't allow integrate OpenZFS into a Linux core, but it's not like ZFS is proprietary
https://openzfs.github.io/openzfs-docs/License.html
While both (OpenZFS and Linux Kernel) are free open source licenses they are restrictive licenses. The combination of them causes problems