OnlyOffice is getting upset that they've been forked, after they attempted to set sketchy license additions to prevent forks:
I explain their questionable license, including a conversation I had with their legal manager, on isitreallyfoss:
https://isitreallyfoss.com/projects/onlyoffice/
I hope Euro-Office succeeds to provide a FOSS-friendly alternative, will need a lot of effort though to continue a project like that, especially if OnlyOffice play nasty.