With Face ID on the, hidden notification previews on the lock screen is the new default setting. Unless you are physically looking at your phone, notifications will only contain the respective app's name.
Hiding notification previews until you're looking at your phone makes sense, but for some users, it's not ideal. I know there are times when I get somewhat annoyed I have to pick up my phone to read a notification instead of leaving it on my desk. But the trade-off of added privacy for a minor annoyance is one I'm willing to make.
Changing the preview setting back to showing anything and everything on the lock screen takes just a couple of taps. Here's what you need to do:
Open Settings > Notifications > Show Previews > Always. Going forward, new notifications will appear as they always have on an iOS device, with message and notification content available for all to view.