According to https://www.libreoffice.org/about-us/licenses/:
LibreOffice is made available subject to the terms of the Mozilla Public License v2.0 which is reproduced below. It is based on code from Apache OpenOffice made available under the Apache License 2.0 but also includes software which differs from version to version under a large variety of other Open Source licenses.
I've looked up the LICENSE file of LibreOffice and found that it included software which are licensed under GPL v2 (e.g. libatomic-ops, poppler, MySQL Connector/C++).
Wouldn't that make LibreOffice, as a whole, a GPL software too?