Relevant parts:
Partner represents and warrants that it shall not introduce into WhatsApp’s Systems or Infrastructure, the Sublicensed Encryption Software, or otherwise make accessible to WhatsApp any viruses or any software licensed under the General Public Licence or any similar licence (e.g. GNU Affero General Public License (AGPL), GNU General Public License (GPL), GNU Lesser General Public License (LGPL)) containing a “copyleft” requirement during performance of the Services.
Partner shall not: (i) combine Sublicensed Encryption Software with any software licensed under any version of or derivative of the GNU General Public License (e.g.; GNU Affero General Public License (AGPL), GNU General Public License (GPL), GNU Lesser General Public License (LGPL) in any manner that could cause, or could be interpreted or asserted to cause, the Sublicensed Encryption Software or any modifications to the Sublicensed Encryption Software to become subject to the terms of any version of or derivative of the GNU General Public License or other copyleft open source software
Just dual-license your software under the TNGPL (Totally Not GPL) license that just so happens to afford the same protections.
Fun fact: the GPL license is itself under copyright, held by the FSF, and subject to certain conditions. That’s why there’s only one “GPL” and it remains the same and everybody can rely on what’s in it.
Besides, they did mention that derived licenses or any copyleft licenses are not ok either.
They actually did not. They clearly state (at least in the text posted by the OP) that you are not allowed to license under a version or derivative of the GPL if it would end up copyleft. The main condition is that it is licensed under a version of the GPL.
(To be clear, I’m talking about the second quote, about combining)