https://www.ldoceonline.com/dictionary/may-just-might-just “Just” here is part of an idiom that conveys possibility and does not mean “simply” or have any meaning that suggests the problem is small. “Might just” and “might simply” do not mean the same thing in English.
This idiom works differently than you think. This thread https://old.reddit.com/r/EnglishLearning/comments/161uisc/what_does_it_mean_you_just_might/ Captures the basic meaning of the idiom “Just” in isolation can mean something different than when it’s added to a phrase. Don’t take my word for it though, Google “might just idiom” for more discussion. This is the thing about idioms, phrasal verbs and the like: they take words that have different meaning in isolation and by joining them alter the meanings of the individual words.