Brave is built on Chromium. So, by default, no they are not safe from this. Without extra effort, Brave will have this feature. I don’t know if its feasible but there’s a chance the Brave devs can remove the code from their distribution, but that’s the best case scenario and just puts them in the same position as Firefox: they get locked out because they refuse to implement the spec.
DRM exists to "protect’ the software developer, i.e. protect profits by making sure every copy has been paid for and to force people to buy multiple copies in certain cases. DRM never has and never will be for your (the consumer’s) benefit.