In his Realm we're playing on, my friend, who plays on the PS5, tried to use the firework with the Elytra, but he died randomly as soon as he used the firework (the death screen even says he precipitated).

Then, there's a 2nd bug (a visual one), which is that after he died, the death screen doesn't show his item drop, which made him think his whole inventory got wiped by the death, but thankfully the items did drop.

Here's a video that shows these two bugs happen. (I wasn't sure whether or not make 2 separate bug reports for these two bugs, but I figured I'd put them in one bug report since they're both in one video, and I don't know if these two bugs are somehow also related to each other).