Here's Starfleet Brasil's site, which I translated into English for those of us not quite bilinguals:
https://translate.google.com/translate?sl=auto&tl=en&js=y&prev=_t&hl=en&ie=UTF-8&u=http://www.trekbrasilis.org/tag/frota-estelar-brasil/&edit-text=&act=url
Apparently, according to the site, Starfleet Brasil took a 13 year hiatus, and when they started up a new convention this year, CBS, the new owner of Star Trek, contacted them and said they could use the term "Starfleet" one more time for this convention, but then no more. They then went on to say that CBS has been on a witch hunt since the lawsuit against Axanar, and that it's stifling fan creativity.
From what I gather, Starfleet Brasil is still Starfleet Brasil, but their conventions can't be called Starfleet conventions. So they changed the name to Starcon, and the latest convention will be called The Phoenix. In other words, it wasn't about their name at all, but that they called the conventions Starfleet conventions, which could most definitely confuse people. Again, assuming this is all true.