Ui's strength is she's always trying to get along with people. Reading body language and those kind of signs would be her social survival skills and came unconsciously.
Would the debuff gone if they kill Glenn? Players revive with clean status, right?
With the mechanism, it probably wouldn't help.
Unlike bad status, it's more like being gaslighted to believe someone else's idea is also yours. Your own mind then try to make sense of it and create all the reasoning to back it up. It became your own thought, so the respawning won't clean it up or else you might as well lose random memories with each respawn.
You have to convince yourself it's actually wrong.
Like in case of Yuusuke's victims. His commands are usually right-now things, so his victims are quick to notice inconsistency and found out something is not right. The one the Dragon Bishop put on Glenn is more long term and harder to notice discrepancy.
Ui noticed it because "the Glenn I knew wouldn't have think like that". That would be harder to notice by the person herself.