IIRC the reasons are detailed in a document[1] that was already shared here before. TL;DR - It appears after the January 8 coup d'état attempt in Brazil, it was opened an investigation to identify who coordinated and who participated in the coup. Then some xitter profiles started a coordinated threat and doxxing campaign against police investigators who took this case. So the brazilian supreme court ordered xitter to provide information and block seven profiles involved in this doxxing campaign, what it refused to do.
[1]. https://static.poder360.com.br/2024/09/decisao-stf-x.pdf (Portuguese)