“He has been imprisoned, but I don’t know why,” Celso Vilardi, one of his lawyers, told the AFP news agency.

Maybe he should read the text of the decision issued by the STF: https://noticias-stf-wp-prd.s3.sa-east-1.amazonaws.com/wp-content/uploads/wpallimport/uploads/2025/11/22083749/Decisao-PP-JB.pdf

The gist is:

• He was serving preventative house arrest due to a high risk of escape, waiting to exhaust his avenues for recourse
• He violated the integrity of his ankle monitor
• One of his sons called for a “vigilance”, essentially to have lots of his supporters out in the streets in front of his residence
• The residence is very close to the USA embassy in Brasília

Putting all that together, it was judged that the crowd could represent a risk to public order and safety, and provide the means for him to escape. He still has close contacts in the USA, and it’s speculated that he would try to reach the embassy and request political asylum.