New answers tagged facebook-pages
I don't now that this is conclusive (eg applies in general) but the top right corner of the first link in the OP has: and the second: so it seems the Create Page or Join Group may be the indication required.
It turns out you need to get a minimum of 25 likes first. Another reason for this message can be that certain words (like 'facebook') are restricted, or that the username was reserved by an earlier page that's no longer up. For more, see also https://www.facebook.com/help/211337555567785
A possible scenario is that the username was taken at one point and then the page was deleted / username changed of the page. This makes the username unavailable for an unspecified period of time.
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