I was wondering about how they came to the conclusion that they violated the copyright, so I went to check if they did the AGPL[1] with some extra clauses in it. Turns out they didn't, but they did change[2] it[3] in an interesting way: All the https urls in the GNU version are http urls.
[1]: https://www.gnu.org/licenses/agpl-3.0.txt
[2]: https://github.com/ONLYOFFICE/core/blob/master/LICENSE.txt
[3]: https://github.com/ONLYOFFICE/onlyoffice-nextcloud/blob/mast...