From the general user's point-of-view: Using OnlyOffice's paid products may be problematic because of sanctions against Russia.

From a contributor point-of-view: If I voluntarily contributed to OnlyOffice, I would be unhappy that the company sold my AGPL-licensed code and attempted to hide the fact. Granted, they probably require contributors to sign a CLA, so as to make this legal. And yes, it is also unclear if P7 was a single-time fork of OnlyOffice, or if it continually takes code from OnlyOffice.

From a random Russian person's point of view, it would be very unfair to learn that the (ostensibly Russian) software you have bought (because P7 appears to be solely commercial, not freemium, but correct me if I'm wrong) is in fact open-source and gratis in the West.