Let's say you were to go through a nether portal. You go through and you see a loading screen. However, if there was a hostile mob in front of you during that loading screen, it could attack you while it's loading. This means a mob can attack you while you are in a loading screen and you have absolutely no control over it. I know why this happens in Bedrock and not in Java. In Java edition, you see the Nether chunks load slowly when you enter it. In Bedrock, there is a loading screen while those chunks are loading. Which means it's not really loading. The way to stop mobs from attacking you is to remove the bedrock loading screen for when you enter a new dimension. Of course, chunks may appear to load slowly, but it's much better than to get attacked by mobs and have no control over it. Please fix this Mojang.