Recently, I reported this issue on PaperSpigot github and it has been fixed there, but I think, this should be done on Spigot level too.

Expected behavior:
When joining, player should receive only one PlayerInfoUpdate packet with initialize action per every player.

Actual behavior:
Player is receiving one PlayerInfoUpdate packet with a list of every online player on the server and then PlayerInfoUpdate packet once per every player whose can he see.

Mentioned issue: https://github.com/PaperMC/Paper/issues/8772

This issue breaks many plugins that modify player-info packet content on the fly.