The bug
When you die, the game will re-send all the chunks, even if the chunks are near where you died.
How to reproduce
Open a server (the laggier, the more noticeable)
Connect to said server
Wait for chunks to load
Kill yourself without moving
→ ❌ All the loaded chunks will be scrapped, causing them to be re-downloaded from the server, using both time and bandwidth
Related issues
is duplicated by
Comments
Confirmed in 1.5pre
confirmed for 15w45a

Is this still an issue in the most recent versions (currently that is 1.10.2, or 16w42a) of Minecraft? If so, please update the affected versions and help us keeping this ticket updated from time to time. If you are the owner/reporter of this ticket, you can modify the affected version(s) yourself.
Status is set to postponed, meaning it's not needed to be up to date as a fix won't be attempted anytime soon.
Affects 1.12 - Pre-release 5

Affects 1.12.1

Still in 19w06a

Still in 19w07a

Still in 19w08a

Still in 19w09a

Still in 19w11a

Still in 19w11b

Still in 19w12b

Still in 19w13a

Still in 19w14a

Still in 1.14 Pre-Release 1

Still in 1.14 Pre-Release 2

Still in 1.14 pre-3 and 1.14 pre-4

Still in 1.14 pre-5

Still in 1.14 Release

Still in 1.14.1 Release

Still in 1.14.2 Pre-Release 1 and 1.14.2 Pre-Release 2
Can confirm for 20w27a

Can confirm in 1.17.1 Release Candidate 1.
Can confirm in 21w40a and 1.17.1
Affects 21w44a
Can confirm.This is the most annoying bug for me because my friend host a small server and its laggy when i die, i must wait the MultiplayerChunkCache to max before i can play without lag
Best to reproduce in default world (superflat are lagless)