Stripping metadata is up to the website / app, not the OS. Many apps use metadata, some don’t. If they don’t need the metadata and decide to do the right thing, then they’ll strip it.
Also upload my Android photos to Ente Photos and the metadata is preserved (thankfully).
AFAIK that would mean ChatGPT and each website (not Firefox) would decide that itself. Firefox doesn’t do it since a website may need it.
It wouldn’t need to be proprietary. The logic could just be “remove everything”. Not sure how the Google Inc thing appeared.