"Immutable": A term to describe Linux operating systems that do not follow the traditional filesystem layout where every single file can be removed by the user with root privileges. It is more nuanced than this in the case of Bazzite, but is still considered "immutable" from the point of view of the extended Linux community. The Bazzite team would not describe Bazzite as an "immutable" operating system.

https://docs.bazzite.gg/General/terms/

I'm a big fan of Bazzite, but as stated in the docs, "immutable" is a term the community uses to describe it.

Education is the key to reducing confusion, not pretending a system architecture doesn't exist or matter.