As Mad said, Ciken ultimately holds the keys when it comes to updating our MC version.
Assuming there's no plugin dependency issues, I'd be in favour of updating. There was a potentially really annoying bug with Vane where you could end up perma-locking items in a backpack by putting a pouch/shulker into it, which is now fixed as of this release: https://github.com/oddlama/vane/releases/tag/v1.16.0.
Once Ciken is back from his lil' holiday I'll bug him about it
In the meantime, if you're annoyed about having to swap versions of MC, I recommend using a multi-instance launcher like https://prismlauncher.org/ or https://multimc.org/. You can then have a setup for 1.21.4, and another setup for 1.21.1 which you just swap between super easily. I use MultiMC for vanilla + Prism for modpacks
