It happen when the server suddenly close while upon death

Do you have the server crash log?

2024-12-16-1.log

My bad the server didn't crash but I was timed out from the server but before that I was blown up by a creeper

The logs are being spammed from Netty Epoll Server IO whatever that is, but other than that there doesn't seem to be anything mentioning that you tried to reclaim the grave.
Were you able to do so, but the block remained, or did you not get any stuff?

I was able to claim it but the block remain I did get the stuff

Hmm that's odd... I'll try to look into it more, but might be a few days. Have quite a few things to do before christmas. Sorry this issue doesn't quite make the same priority list

It happened to me as well