One-cycling the Ender Dragon, a common practice amongst speedrunners nowadays, does not work on Spigot.

Normally, the speedrunner will place a bed on top of the bedrock pillar in the center of the End, and wait until the Dragon is in the optimal position to explode it. Once the bed explodes, the Dragon needs to "try again" when perching, and stays in its position in the air. Another bed can be used to repeat this effect, and so on. You can view this on https://www.youtube.com/watch?v=Bf1qdEN32DI.

On Spigot, however, the Dragon simply ignores the bed explosion and automatically perches, making one-cycling impossible despite it being a vanilla feature of Minecraft.

To test what I mean, you can get an experienced speedrunner to try to one-cycle the Ender Dragon on a 1.16.4 Spigot server. It simply cannot be done. I have seen this work on some forks of Spigot, although I cannot confirm a version number of said forks. On 1.16.4, Spigot, Paper, or any other fork of Spigot does not fix this bug, nor does CraftBukkit.