Following the reproduction process I identified for MCPE-23416, MCPE-97295, and MCPE-141499, I discovered that a similar process can cause the generation of terrain features to be cut off at chunk borders. When a terrain feature such as a tree crosses a chunk border and only one of the two chunks has come within a player's simulation distance, the part of the feature in the neighboring chunk can fail to generate if the player moves in such a way that the never-simulated chunk is unrendered and then comes within simulation distance of the player during auto-saving.

Steps to reproduce

1. Set render distance to 8 and turn on the auto-save icon.
2. Create a world with creative mode, seed 1686104715, simulation distance 6, with coordinates on.
3. Move to 130, -12 without going any farther north than Z = -12. Notice the red mushroom tree in the distance.
4. Move to 130, 100 and wait.
5. When the auto-save icon appears, fly straight north to the red mushroom tree you saw in step (3).

Expected result

You arrive at a complete mushroom tree.

Observed result

You arrive at a slice of the mushroom tree cut off at the Z = -112 to -113 chunk border. How to cut off generation at a chunk line .mp4

If you don't get it, try again--I reproduced this 3 times in 7 or 8 tries. I think the key may be simulating the mushroom tree chunk ASAP once auto-saving starts.