Yup - she's already taking heat for flying again, even if it's commercial. And of course she'll take heat for leaving Archie behind. I left DS for 12 days when he was 6 months old so I'm not feeling terribly worked up about her leaving Archie for 2 days at 5 months personally.
The people who are outraged by her "lavish" lifestyle will not change their minds whatever she does so I imagine they take the view there's no point even attempting it.
And the conspiracy theorists (eg the ones who think Archie isn't real) won't be changing their mind so she may as well get on with her life and let them get on with theirs.
I' tell you what I'd be doing if I was their PR adviser (all royals, not just MM and PH) - I'd be trying to find a way to show what they're doing in background. In the SA tour details there's something about a programme that harry has been working on with various groups. We get glimpses of this kind of thing all the time. Harry and Meghan at least show some of it, but the others don't - it's all very discreet and in the background. But they need to start getting people to see them as CEOs not shop assistants - ie they might not be visible but they're there doing things and making decisions and driving partnerships to make other things happen....