“Logged when asked for f3” means that a staff member had called out a player, usually with colored text (also normally red) and asks them to stop what they’re doing, and take a screenshot of their f3(debug) screen and send it to them. Your friend may have tripped the anti cheat and caused a staff to investigate them, resulting in the staff asking for proof if they were cheating. Logging during this process normally results in an instant ban.