My game freezes after 10-30 seconds of playing in a world.

This is on version 1.12 on Minecraft pe. It wouldn’t let me choose that version in the version section. My game continuously freezes after playing in a world for 10-30 seconds and I've repeatedly restarted my phone and my data is fine. Nothing helps/works for this issue.

My game also keeps saying that I need to change my skin because it is not available for multiplayer but it's the Steve/Alex skin so it has to be multiplayer because they're the defaults. Please fix these issues.