Just out of curiosity: the press releases I've seen about these big government players switching to Matrix generally mention that they're using a customized cli

Just out of curiosity: the press releases I've seen about these big government players switching to Matrix generally mention that they're using a customized client of some sort. That's understandable, but what I want to know is: Have they also customized the underlying protocol by which their homeservers communicate? The reason I ask is that it seems to me (as an entirely uneducated outsider) that if they're using the Matrix protocol as-is, then they have incentive to support and assist with the further development of the Matrix protocol, which is great. But if they've already started customizing it, then I would worry that they eventually will decide they don't need Element or the main Matrix protocol and will just go off and do their own thing.