Exported Mod creates crash

I don't know how to describe this because I don't know how or why it is happening.

My specs:

MCreator 2025.3

Making a mod for Fabric, 1.21.8

I have spent weeks working on a mod, and using the Gradle export function within MCreator I have exported it, as a java file, and placed it into the mods folder. Simple test mods have worked doing it this way using the same version.

However, when I load up Minecraft, the launcher kicks me out with error code 1 (despite it working when running and debugging within MCreator)

I did some further digging and got to the error messages themselves:

[14:52:17] [main/ERROR]:Mixin apply for mod my_mod failed my_mod.mixins.json:PlayerMixin from mod my_mod -> net.minecraft.class_1657: org.spongepowered.asm.mixin.injection.throwables.InvalidInjectionException Critical injection failure: @Inject annotation on tick could not find any targets matching 'tick()V' in net/minecraft/class_1657. No refMap loaded. [INJECT_PREPARE Applicator Phase -> my_mod.mixins.json:PlayerMixin from mod my_mod -> Prepare Injections -> handler$zpk000$my_mod$tick(Lorg/spongepowered/asm/mixin/injection/callback/CallbackInfo;)V -> Parse -> -> Validate Targets]

(Followed by over 100 lines of further messages, all about the same error e.g.

at org.spongepowered.asm.mixin.injection.selectors.TargetSelectors.validate(TargetSelectors.java:346) ~[sponge-mixin-0.17.0+mixin.0.8.7.jar:0.17.0+mixin.0.8.7]

I have done research and genuinely have no idea how to fix this, but I also can't see anyone else having the same issue.

Anyone have any ideas?