I remember this, the mangaka said she was aware of the English TL, but I think she was neutral on it. Unfortunately that changed when the series got officially licensed
Considering how apologetic and remorseful she's been over it, I'd assume it's something real she did to him. Also based on how she's currently getting bullied by others I imagine she used to be a bully, but lost her power or her posse, and is now on the receiving end
Honestly I kind of like it. It's pretty generic strong guy trying to act normal, but I like the introduced characters so far, and being an assassin I like mc's abilities
If Yuria has heard the rumors of Mimir as well then it's impossible Ars is him. Ars has been locked away and isolated, I don't think that would give him any opportunities to spread rumors about himself or do acts which would relate them
I think it was just framed poorly, it seems Mimir is the one who's been stealing secrets, since he's known across nations for this act. Meanwhile, Ars escaped today I presume, so it's impossible that it'd be talking about him, he was isolated and hidden for 10 years and has had no chance to make...