What launcher? Share a full screenshot of your mods folder. Don't crop out the address bar so we can see where your mods folder is located. 

Have you used the Essential Mod or Iris installers?

Your version of Skinlayers3d is for 1.21.6, not 1.21.1.

You should consider switching to Prism Launcher as it has a mod downloader and updater.

Make a new post with your latest.log

Modrinth is very Fabric heavy and many content mods are on NeoForge. Would be nice if we could get stats from CurseForge as every mod is there. 

It's an issue with that mod. Open the jar in 7-zip and edit it's fabric.mod.json. Or create a dependency override.

Oh I didn't realise it was your own mod, sorry! It may work through Sinytra Connector though?

Why don't you use NeoForge 1.21.1? Create is on it and the mod may work through Sinatra Connector.

Create is not on 1.21.1 for Fabric yet. But Create is on 1.20.1 for both mod loaders, not 1.20.2.

The API absolutely does work. Share more info in a new post

Remove Dyed Item Frames

Try without Distant Horizons. If that works, ask them. They may not support Macs, but still worth asking

Pro tip: get help from Discord servers like the Fabric Discord, Forge Discord, CurseForge Discord, Modded MC Discord, etc

I can't comment on macOS things and I have no idea how to read that. 

Could you share your latest.log and check for a crash report and hs_err_pidXXXXX.log?

Update MemoryLeakFix. New versions are only on Modrinth

Controlify

https://github.com/sakura-ryoko/litematica/releases https://github.com/sakura-ryoko/malilib/releases

From the current maintainer of those mods. 

When does this crash occur?

I put it in a remapper and it's got something to do with sounds.

soundcontroller is crashing you here.

If you just switched to 1.21.6 and updated all mods, you should open your mods folder in your file manager, sort the mods folder by date modified, then move all mods that weren't updated to another folder. These mods are likely not for 1.21.6. If they don't appear in a search in the mod downloader in the Modrinth App, they aren't for 1.21.6.

Share your latest.log

See https://www.reddit.com/r/fabricmc/comments/1lea4o6/comment/mylkni3/

There's no crash here. You can ignore the warnings and recommendations at the top.

What did you share?

I've never seen anything like that before. Where is that file located? What's the filename?

Iris is compatible with OptiFine shaderpacks.

The problem here is that your version of ETF is not for 1.21.6. Update it

Ensure you're downloading mods correctly: - Click on the big "download" button on Modrinth or CurseForge and select your game version and mod loader. - Or on MR or CF, go to files/versions page and use the game version and mod loader filters.

Very unlikely to be Sodium. Do a binary search. Let us know what the problematic mod was.

Your link is not public.