Is there actually not a catch here? I'm only somewhat familiar with the debate.
The only point of contention is what happens to their new product, One D&D, which will probably retain some nasty payment structure, and almost certainly not be OGL'd. That's fine though - if they build a walled garden around One D&D, they simply won't be able to compete against the open community of 5e.
They can't change that particular SRD, but material not in the SRD can be changed as can new material. Also, as they leave the old OGL intact, it is a catch in itself: 1) It's generally restricts rights much more than grants them [0], and 2) WotC believes they can revoke it at any time.
[0] https://www.eff.org/deeplinks/2023/01/beware-gifts-dragons-h...