Well, millenial here and a lot of what she's saying is true tbh, however, you can elect for it not to be true as well, as I do and save your health and sanity.
If people email me about work after work hours, I answer it after 9.00am the next day, people I'm friends with know if I'm doing real life stuff with my partner or family and they text or message, I'll reply when the real life stuff is over, i'm not going to be checking my phone every 5 seconds when we're eating dinner etc, that's rude and the expectation of an instant reply leads to stress, so I don't do it.
I don't like Kale, so I don't bloody eat it, there is no Kale Police. I don't wear makeup unless i'm at an event , for my partner or we're going somewhere and something special is happening, partly because I don't have the time and partly because there should be no expectation of anyone for me to do so when I'm at home.
I've decided that there are other priorities now for me than my career, so I'm winding back on aspects of it that are not flexible and that are causing me stress, I have no social media presence now (which is lovely) and I absolutely refuse to be controlled by anyone else's opinion of what they think I ought to be or be doing (except my partner).
The problem with Millenial Burnout is that it's entirely a self promoted malady, and people have it in their own hands to opt out of all the BS that causes it, so they should.