When I place down a sculk catalyst next to a sculk block, I see that the sculk block is animated and that the catalyst isn't.
I use the mods:
Appleskin, BetterF3, Boosted Brightness, Cloth Config, Continuity, EntityCullingFabric, Fabric API, Forgetmechunk, FPSDisplay, FPSReducer, Indium, Iris Shaders (they are disabled), LambDynamicLights, LazyDFU, Litematica, Lithium, Logical Zoom, Malilib, ModMenu, NoFog, ReplayMod, ShulkerBoxToolTips, Sodium, Starlight, and WorldEdit.