yes.

https://www.heise.de/news/Whatsapp-muss-sich-oeffnen-Threema-und-Signal-winken-ab-9636224.html

Signal does not want to lower its standards for WhatsApp either. “Our privacy bar is extremely high, and not only will we not lower it, we want to keep raising it,” says Signal President Meredith Whittaker. “Currently, working with Facebook Messenger, iMessage, WhatsApp or even a Matrix service would mean a degradation of our privacy standards.”

[Translated with DeepL]