She's out on recon because the Hero party's actions doesn't line up with the Hero's personality. In the previous battle, the Hero brought a kid (succubus lady's sister) to a dangerous battle. When they were about to lose, the Hero used a teleport home glitch that only people who played the game know.

Now they're talking about how the Hero's team knows information about the area the MC and co. are based in. The party even set up a base of operations nearby. How did they get the info? Lizardman leader explains that it was probably from a lizardman scout. The problem is that lizardmen don't easily betray their allies. So the only conclusion is that the scout was captured by the Hero party, and tortured to reveal info to them.

This is "weird" to the Lizardman leader and the maid because the Hero isn't that type of person (hence Hero). The sister kid mage is also out of the question. So who's doing things like torture and feeding glitch tactics and info into the Hero? That's what she wants to know.