First, near as I can tell, they only claim you need a patent license if you distribute an encoder/decoder. MPEG-LA has claimed distributing encoded video needed a patent license as well, but backtracked on trying to charge for it.
Second, your agreement to license your own patents only covers Necessary Claims on the Implementation (both the specific implementation you're distributing and the reference.) Which by definition can't cover any future inventions, because if the implementation already infringed them then they aren't novel inventions. But it does explicitly claim to include IP you acquire in the future that applies.
Also, I think the intention is that the license you have to grant only covers implementations of AOMedia standards; if a VVC implementation or whatever also used your invention, that would probably need a separate license you could charge for.