I suspect onlyoffice will win this one
I'm sceptical tbh, their interpretation of the AGPL seems questionable. The specific wording in the AGPL they're relying on for their logo preservation term is:
Requiring preservation of specified reasonable legal notices or author attributions in that material or in the Appropriate Legal Notices displayed by works containing it
IMO a logo isn't attribution, and even if it was there's no way it could be considered reasonable to require it if they don't allow you to use it.