• Only the latest version is being supported. If you are using an outdated version, upgrade to the latest version.
• Provide instructions for how to reproduce the issue. Include the Minecraft version and mod version.
• Forge version issues belong to https://github.com/qouteall/ImmersivePortalsModForForge/issues
• If it's a mod compatibility issue, post that mod's link and open another issue on that mod
  the game doesn't start
  mod is CaffeineMC/sodium-fabric
  apparently, it doesn't allow sodium
  crash report:
  Incompatible mod set!
  net.fabricmc.loader.impl.FormattedException: Mod resolution encountered an incompatible mod set!
  A potential solution has been determined:
  • Replace mod 'Immersive Portals' (immersive_portals) 1.2.5 with any version that is compatible with:
    • sodium 0.4.1+build.15
      Unmet dependency listing:
  • Mod 'Immersive Portals' (immersive_portals) 1.2.5 is incompatible with any version before 0.4.0-alpha6 or any version after 0.4.0-alpha6 of mod 'Sodium' (sodium), but a matching version is present: 0.4.1+build.15!
    at net.fabricmc.loader.impl.FabricLoaderImpl.load(FabricLoaderImpl.java:190)
    at net.fabricmc.loader.impl.launch.knot.Knot.init(Knot.java:142)
    at net.fabricmc.loader.impl.launch.knot.Knot.launch(Knot.java:71)
    at net.fabricmc.loader.impl.launch.knot.KnotClient.main(KnotClient.java:23)

use sodium 0.4.1

I am using the latest 1.18.1 version of sodium

It's recommended to use 1.18.2. In 1.18.1, the compatible sodium version is 0.4.0-alpha6