Recently I tried to change my minecraft profile name (java edition) to 341. I checked its avaliability through https://api.mojang.com/users/profiles/minecraft/341 and it return HTTP 204, indicates it doesn't exist.

But when I browsed to my profile on www.minecraft.net to actually change my profile name, it says this profile name already exists. I tried to use https://api.minecraftservices.com/minecraft/profile/name/341 and it returned HTTP 403, indicates that I can't change my name to 341.

Seems this is not an issue of blocked usernames, as I checked all 46,656 possible 3-character profile names, over 500 names returned no content (mostly random strings like R9Z, S83, R_3, SLG), but I manually checked almost half of them on profile page on www.minecraft.net and it says every one of them already exists.

I can think of no other reason why a profile name doesn't exist but is still unavaliable, so I think it may be a bug of mojang API. But maybe there's another reason, and if so please tell me.

Thanks for helping!