1.17 worked just fine for me, but 1.18 refuses to work. Tells me I need to update Gekolib3, which I have. I'm still told it is out of date. It's the 3.0.3 (Fabric) version (ie, latest)

The exact message states;

"ModResoulutionException: Mod resolution encountered an incompatible mod set!

A potential solution has been determined:

  Install geckolib3, version 3.0.20 or later."

Everything is updated as of 12/22/21. I'm not sure exactly where the problem is so I'm posting this here and on the Gekolib page.

Gekolib has already gotten back to me and they have stated that the issue is not on their end. They suggested I come to you, which I thought I already had. Apologies for my lateness.

This mod is the only one I use that requires Gekolib. I really love this mod and I don't want to have to stop using it because it crashes. I hope that there is a fix for this.

As I said in the comment of yours a few days back, the 3.0.3 file of geckolib is outdated and/or not fabric. The latest FORGE file is 3.0.3 yes, but the latest fabric file is 3.0.23 and can be found here https://www.curseforge.com/minecraft/mc-mods/geckolib/files/3557186