hey there, I am making my first mod as well, and I'm having the same problem as you. Can I please get some help I have no clue what to do.
[14:24:22] [main/WARN] (mixin) @Mixin target net/minecraft/server/world/ThreadedAnvilChunkStorage$EntityTracker is public in fabric-networking-api-v1.mixins.json:accessor.EntityTrackerAccessor and should be specified in value
[14:24:22] [main/WARN] (mixin) @Mixin target net/minecraft/client/particle/ParticleManager$SimpleSpriteProvider is public in fabric-particles-v1.mixins.json:ParticleManagerAccessor$SimpleSpriteProviderAccessor and should be specified in value
[14:24:22] [main/WARN] (mixin) @Mixin target net/minecraft/data/server/AbstractTagProvider$ObjectBuilder is public in fabric-tag-extensions-v0.mixins.json:MixinObjectBuilder and should be specified in value
[14:24:22] [main/WARN] (mixin) @Mixin target net/minecraft/tag/RequiredTagList$TagWrapper is public in fabric-tag-extensions-v0.mixins.json:MixinTagImpl and should be specified in value
[14:24:23] [main/WARN] (FileUtil) Configuration conflict: there is more than one oshi.properties file on the classpath
[14:24:23] [main/WARN] (FileUtil) Configuration conflict: there is more than one oshi.architecture.properties file on the classpath
[14:24:30] [Render thread/INFO] (Minecraft) Environment: authHost='https://authserver.mojang.com', accountsHost='https://api.mojang.com', sessionHost='https://sessionserver.mojang.com', servicesHost='https://api.minecraftservices.com', name='PROD'
[14:24:31] [Render thread/ERROR] (Minecraft) Failed to verify authentication
In bold is the problem I'm not sure how to fix.