iChunUtil is a shared library used by iChun’s mods. If an iChun mod’s version does not start with 1.x.x, it probably requires this library. Available for Forge, Fabric and NeoForge, iChunUtil covers Minecraft versions 1.7.10–1.21.5.
For an iChun mod that needs this dependency, rent your own Minecraft server and install iChunUtil with one click from the server panel.