Soo, whenever I leave a server, my player will remain in the world for another 30 seconds, meaning in that time I'm vulnerable to all mobs, and I even died multiple times.

The server log even says: 

[19:09:00 INFO]: VenRoot lost connection: Timed out
[19:09:00 INFO]: VenRoot left the game

Found out that it's happening on multiple hosts. 

But that doesn't always occur, somtimes I properly disconnect:

[19:05:07 INFO]: VenRoot lost connection: Disconnected
[19:05:07 INFO]: VenRoot left the game
 
It really annoys me, since I died multiple times already to some mobs.
 
I even tried it with 1.16.4 and... same issue