Players will not leave tombstones and equipment items will simply disappear as they instantly heal abnormal deaths caused by level 125
1.20.1

What

What
In the Java version, using a potion with an instant healing effect (i.e. Amplifier value of 32n + 29, where 0 ≤ n ≤ 3) can directly kill non-undead creatures, including in creative mode. If a player dies as a result, there will be no death message on the death screen, and it will not increase the death count on the scoreboard. Additionally, this type of death does not leave a grave, and even items will disappear directly, which is why this issue has been reported.

So you die in a bugged way, which breaks graves. Yeah it's issue with vanilla then, so not sure if it's worth fixing it

So you die in a bugged way, which breaks graves. Yeah it's issue with vanilla then, so not sure if it's worth fixing it

Thank you for your reply, but do you know if there is any module that can automatically back up the player's backpack? I'm afraid I'll be in this situation again

After checking yeah, you also lose items in vanilla, as it doesn't run any of death logic. Closing