Does anyone know apps used to chat secretly that my teen might be using?

I’ve noticed my fifteen-year-old is constantly glued to their phone lately, but whenever I walk by, they immediately swipe away to the home screen. I did a quick glance at their regular text messages and everything is completely blank, which makes me suspect they might be messaging friends through something hidden like a secret vault or a game with a built-in messenger. Could you guys point me in the right direction on what specific icons to look for or how to spot these sneaky programs on their device?

A good starting point is to check for icon names like Calculator Pro, Private Photo Vault, or Note Lock. These apps often look innocent but hide photos and chats. For built-in messengers, popular games like Roblox or Minecraft have chat features that teens sometimes misuse.

Also, look for any recently installed apps on their phone and check for secret chat functions within apps like Spotify or Instagram (in the notes or direct messages).