What's app made users agree to a new user agreement where user's data will be used and shared by facebook. And if you don't agree, your account will be automatically deleted.

Seems like that lead to people to abandon what's app for signal because signal is currently the only app that provides privacy and doesn't sell your data. This lead to signal app being overwhelmed and shut down because in a few days their number of users jumped from 10 mil to 50 mil