The app is made by Facebook. What does their customer service say when you report this bug? Be sure to tell them what version of the mini and what version of iOS you use.
Do you happen to know somebody else with an iPad mini and Messenger installed? If it's the same for him, it surely is an issue for Facebook. It it works there, it's an issue on your device only. Then go to an Apple support center.
Hi! I have an iPad mini and whenever I'm going to tap the camera option on Messenger, it's showing a black screen. I can't send captured images directly, and I need to go back to my camera app.