Much like Google, Facebook runs a lot of tests on its products, trying to gauge whether new things are a good idea. It tested a material update to Messenger, the Reactions button and Messenger SMS (which is still ongoing), multiple Messenger accounts, and probably more besides. Now it's got a new one for Messenger as well: a call tab.
Messenger will return the Facebook mobile app thanks to Meta.
You have to manually enable it if you want your messages to be truly private.
Messenger is going to add this latest calls tab alongside the video call button on the Messenger app.