On Minecraft 1.20, Fabric fabric-api-0.83.0+1.20, Mythic Metals mythicmetals-0.18.1+1.20-hotfix, when Alloy Forgery mod is not installed, crash on startup, complaining absent Alloy Forgery.

On previous mod version mythicmetals-0.18.0+1.20 this error was not appeared.

Yes, this is intentional. The mod is fundamentally not playable without it, and this was an oversight which was corrected in this fix.