I'm making a mod pack (Essential mod, Fabric API, Opti-Fabric, Silk Touch Spawners) and every time I launch Minecraft, here's a screenshot.

no clue if it'll show, but the link is "net/fabricmc/tinyremapper/IMappingProvider" and if needed i can copy and paste the stack-trace, but its a bit long.

i forgot to add this, but heres the mod list

Use Fabric Loader 0.14.25, also next time please do a search to see if your issue has already been solved. If this solves your issue please close the ticket.

i'm using curseforge app, is there a way to change what version the fabric loader through curseforge? also not using curseforge isn't an option, as my friend's only way to access mods at this moment is curseforge.

A 5 second search on google would have provided you that answer. However, since you didn't take the time to look and see if you could find the answer, here: https://shockbyte.com/billing/knowledgebase/658/How-To-Install-Fabric-On-Your-PC-Using-CurseForge-or-MultiMC.html