For open source messengers, you can check whether they actually encrypt your messages and whether the server has access to your encryption keys but what about WhatsApp? Since it's not open source, you can't be sure that the encryption keys aren't sent to the server, right? Has there been a case where a government was able to access WhatsApp chats without reading them from the phone itself?
Any source for that claim?
I mean, it's possible given their resources... It just takes long enough to be unfeasible. Also, in special circumstances they can Pegasus your phone and obtain the info without decrypting... Not like you're not screwed anyways when it comes to such drastic measures.
Relevant xkcd as always https://xkcd.com/538/