Unable to change to my previous name

I have 2 minecraft accounts, 2 different names. 1 is SerthonY and 1 is Abyssmaster. I wanted to swap the names, so I changed SerthonY username to a random name and waited for almost 3 months now and still couldn't change my Abyssmaster account's name to SerthonY. I am wondering if my name is blocked? Because it says username is not available and it shows that my name is available in https://namemc.com/