One example I can think of is Widevine DRM, which is owned by Google and is closed source: https://en.wikipedia.org/wiki/Widevine
Google currently allows Mozilla (and others) to distribute this within Firefox, allowing Netflix, Disney+, and various other video streaming services to work within Firefox without any technical work performed by the user
I don’t believe Google would ever willingly take this away from Mozilla, but it’s entirely possible that the movie and music industries pressure Google to reduce access to Widevine (the same way they pressured Netflix into adopting DRM)
Gosh darn it I only just onboarded to Omnivore a few months ago Now I guess I need to find a new place to store bookmarks