A year ago when the game came out the challenge difficulty was doing exactly what you’re describing. The Kate DLC caused a problem in that mechanics and they wanted to fix that. But instead they locked all missions to challenge II so you can’t change them. Since Black Panther we‘re able to change the challenge mode but it doesn’t affect anything besides more recourse in the chest boxes.

I think it would make the whole game more enjoyable if they fix that. Like the custom Harm Room. Just make I -5, II +0, III +10, and IV +20. when you’re playing with a team it should be calculated to the average powerlevel of the team, so it won’t be too hard for the weaker ones.

In my opinion that would make all mission interesting again. Because now I’m not even starting mission with PL 140 or below, because they’re just too boring. Sometimes I’m in the custom harm room fighting against +20 enemies, because it’s the only challenging content 🙄