The bug
When the player dies, a massive lag spike occurs which makes the game very laggy and causes biomes not to "display" even if chunks are loaded.
How to reproduce
Press
Alt+F3
to display the F3 menu with the graphicsRun the
/kill
commandLook at the graph on the left and observe the sudden massive lag spike
Example
Here is an example in video:
[media]Linked issues
is duplicated by
relates to
Attachments
Comments

This might actually be the same issue as MC-4890, not sure.
The issue is still on 1.15.2
Confirmed for 20w14a
And it's still in 21w08b

Can confirm in 1.17 and 1.17.1 Pre-release 1.

Can confirm in 1.17.1 Release Candidate 2.

Can confirm in 21w42a.

Can confirm in 21w43a.
I can confirm this for Minecraft Pre-Release 1 1.15 and it is more of the player stuttering then lag when respawning.