As said above, almost every time I try opening Minecraft while connected to WiFi on my phone it closes. I can go back in as many times as I want and it keeps closing. It occasionally will stay open and I can play, but this normally takes about three-five times of reopening Minecraft. The only way for me to prevent it from closing is to disable my WiFi, but then Minecraft takes absolutely forever to open and I can't open any worlds; it just goes back to the "My Worlds" screen repeatedly. I guess this is two bugs.
Edit: this is on the iPhone XR.