Yes, most likely it will be fixed on Monday.

Whatsapp found a bug and is looking to deploy a fix on Monday. [https://bugzilla.mozilla.org/show_bug.cgi?id=1849150#c13 Bug 1849150] - Cannot paste text in WhatsApp on Firefox There is no need to add any more comments to the Bug as it would likely be considered spam, especially comments like "I get this too" https://bugzilla.mozilla.org/page.cgi?id=etiquette.html /edit: WhatsApp has fixed the bug according to https://github.com/webcompat/web-bugs/issues/125920