Apparent thread block from Player.spigot().respawn()

Created as per original Spigot thread

Clip showcasing issue in latest Spigot version vs older versions (where it was not an issue at all). Most noticeable in KitPvP respawn use case

Demo plugin with this code attached

How to test / replicate

1. Try attached plugin with Spigot 1.8.8; no delay will be observed as in video
2. Try attached plugin with latest Spigot (1.19.2); a 1-2 second will be observed as in video. Appears to be thread block of some kind