I found SJRCraft and it is a semi vanilla SMP on 1.21.11 with a brand new world for Season 8 called Spring Awakens.
It is whitelisted and the staff reviews applications so it stays safe and positive. The server is kept small with a 60 player limit so it feels social and you can actually get to know people.
There are quality of life upgrades and an optional modpack. The season is spring themed with events happening each week like hide and seek build challenges treasure hunts PvP and quiz nights.
There is a shopping district at spawn where players can set up shops and trade. They also do community challenges plus giveaways for active players. Big events are planned too like an Ender Dragon launch and even a Warden boss battle.
