Trump Indictments, page-2452

The conditions in which detainees are held are the decisions of the District of Columbia Department of Corrections and the nature of the charges.

"dozens deemed to be dangerous, flight risks or at high risk of obstructing justice were ordered held without bond. Washington jail officials later decided for safety reasons that all of those defendants would be placed in so-called restrictive housing, which meant 23 hours a day of isolation."

https://www.politifact.com/factchecks/2021/jul/28/instagram-posts/defendants-jan-6-capitol-riot-arent-trespassers-th/