The AGPL is not the issue. The CLA is. It allows the project to change licenses at will, without going back to all contributors and asking for approval.
I mean I dislike CLAs personally, but I understand why they can be healthy for a project growth.
These two things are being conflated in this discussion. One thing is a CLA and copyright/license changes. The other is the license itself.
The last time I saw a FSF CLA, it was part of a larger agreement that also imposed obligations on the FSF.
In the long run, there may be risks to the FSF holding so many copyrights. But I don't think it clarifies matters to treat the FSF's CLAs the same as ones used by a "open core" VC funded startup.
Especially when the for-profit company openly announces this assignment of rights is for the purpose of selling code you wrote to others without giving back to the authors.
The FSF doesn't have a track record of asking for CLAs, and then selling your code to others under different licenses and pocketing the profits.
Source: My PR was merged in 2021, the changes are still part of Synapse, and I never signed any CLA. I don't think they'd be able to get enough sign-offs from historical contributors to pull off any actual shenanigans with the Synapse license.