SMP is now on the latest version of Minecraft! Read up on what’s all changed here in 1.21.9 on the Minecraft dev blog.
You can still join with older versions, but I recommend updating to this version as soon as you can to take advantage of these new features.
Did anything break?
Like most Minecraft updates, things will often break when updating.
In this update, it was necessary to reset the Nether and End due to their respective world-gen datapacks being updated less frequently. Plugins are mostly unaffected. A handful of ProjectKorra abilities using specific particles may have issues, but will be resolved soon.
As always, if you have any issues, let me know!
-cozmyc