i have noticed this bug in the beta/preview, i guess it followed over to the hot fix cause im havin this same problem too, causes the game to unintentionally pause when you look down, the cursor leave the game, its a terrible bug that needs to be squished
im still having that same issue with the current update/hotfix in bedrock, i had tested this on java and the mouse cursor stays locked to the center of the screen when looking around, mojang need to fix this issuse on bedrock asap