To reproduce this bug, create any new survival world, leaving all settings on default. Then start moving away from the world spawn in a single direction through the game world. Eventually anomalies like the one shown in the screenshot will be spotted, and/or the game will freeze, then appear to crash and close down. Upon loading into game again, the player may have been reverted to a previous location and time prior to the crash, although it is never considerably far. If the player has found a saddle and horse, or other pets, they may have been despawned.

I have seen this bug occurring in my established world which was started during version 1.4. However, in this world, the crashing and the despawning of mobs is much more severe, in terms of how frequently it happens. So much so that the game becomes unplayable. I have discovered that the game crashes in exactly the same way, however, when I try to recreate it in arbitrary amounts of new worlds and then move long distances from the world spawn.

This bug has been occurring ever since 1.13.0 when foxes were introduced. I have been searching the site for a bug report that describes it accurately or consistently with the way I have been experiencing it, but I have never found it. If this report I am writing now gets marked as a duplicate that will be very frustrating, although understandable.

I really want to see this bug identified and recognized so it can be fixed, because for someone like me, it kills my interest in the game because it raises the suspicion that the world may be getting corrupted, and it destroys pets that may have been difficult to obtain and the player may have become quite attached to. This bug makes me play in constant fear that my time invested in a world, and all the builds in it, might be a waste if the game starts crashing aggressively and becomes unplayable.

Thank you developers, I hope that my report is original and can at least be helpful to resolving this bug so I can return to playing Minecraft bedrock.