mc1.21.4 beta is missing Enhanced Block Entities (mod is updated but has bugs) and leaf culling. Also missing Animatica, CIT Resewn, FabricSkyboxes+Interop, and Snapper. Other than that, it should be pretty stable.
Most of the mods in the modpack have been updated. Fabric loader has been updated.
Improves vanilla parity with mob spawning. This should not matter if you play on servers. If you play in single player and need the most performance, you can change it back.
Other changes can be found in the commit history.
Please report them on the issue tracker. I'll try to get to them whenever I can.

Vital - это сборка модов для Майнкрафт, которая заменяет Essential и OptiFine. Включает бесплатный хост миров, косметику, шейдеры и мощный прирост производительности. Скачайте Vital, чтобы получить всё лучшее от двух популярных модов в одной оптимизированной сборке.