I found not occupied 3 letter name in namemc and wanted to change mine to this one, but I have the message This profile name already exists
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Comments 3
This name is not available right now, this could be for several reasons. Good luck with finding another suitable name!
The name isn't actually available. There are some names that are permanently "blocked" by Mojang meaning they aren't claimable no matter what. These are caused by the name being inappropriate by Mojang's filters or the account the name used to be on being deleted. btw, there are no available 3 letter usernames.