The Sexist Bernie Bro smear isn't scrutiny of the candidate, it's broader culture/class war stuff, similar to Warren's support base being critiqued as consisting of faux-progressive suburban white wine moms by the Bernie-left. It's essentially background noise that has more to do with the deep cultural shifts taking place in our society than it has to do with the actual candidates themselves.
Problem is that most of MSNBC trash coverage is focused on this type of arbitrary nonsense. It's why I've emphasized a few times that Warren losing voters to Pete rather than Bernie should be something yall pay closer attention to. The narrative flipped on Warren and started to focus on Pete's big Iowa and NH push and now we've got Pete flying up while Warren slips. When MSNBC was gushing over her and the media pushed the "Bernie should drop out narrative" no one was worried and by that I mean not even Sanders supporters. The media cycle just does this. She can and should bounce back once people look past the periphery crap and discover that Pete's a poor man's Joe Biden with a better vocabulary and more recent race based bad decisions.
What I'm talking about is scrutiny of the actual candidate and their plans. Warren has had to handle multiple General Election-type smears and critiques thrown at her from the start of her campaign. Bernie has honestly had little to none. Warren has had personal smears and attacks on the Native American thing, the pregnancy thing, the private practice thing, the private school thing, and the brunt of all policy attacks on M4A so far. She's easily been the recipient of the most bad faith attacks and yet is still the only candidate whose overall trajectory over the entire race has been a sustained rise. If Bernie was getting the same level of critiques, we'd be hearing about his rape essays and his praising of the Soviet Union and his wife's college scheme and his lack of details on M4A, etc. He's being allowed to skirt by without a full oppo dump because the mainstream establishment and press foolishly view him as a sideshow or afterthought. They don't take him seriously. If he wins the nomination, that will change.
The scrutiny on her plans is self-inflicted. For one, she built her brand on "I have a plan" which was begging for attention in that direction (and also something I loved about her approach). For two, by going with means testing, she's given herself a more complicated policy set to sell. Not worse, not better, more complicated to get across because of the "who qualifies."
In terms of bad faith attacks. I'm a Tulsi hater, but she BODIES the field in terms of bad faith. The former nominee called her a Russian Asset and she continually takes hits that drag honest critiques into the hyperbolic extremes mode. Andrew Yang has a fair complaint too. He's ignored and when he does get coverage, they screw up his name in insulting ways. He's another one that I think SHOULD face scrutiny for his ideas, but most of the shots at him are bad faith instead. And then we get to Bernie who already had to deal with those attacks in 2016. He's also been treated as just an angry old man. His name was ambiguously missing in a number of poll reviews that hyped up the rises of Warren and Pete during periods where Sanders was in second place. Plus probably the most ridiculous display of just dishonest behavior, they colored him red on CNN!
It's true that his proposals don't receive any coverage whatsoever. Not positive, not negative, they don't tell you much about those plans. That's why most Bernie heads have to go and explain that ish themselves. But the "Bernie doesn't have details" stuff is pretty damned overblown in its own right.. The payroll tax has always been an obvious funding mechanism for M4A (acknowledged by Yglesias in a side by side comparison of Warren's and Bernie's plans). The rollout for M4A has been fairly well known too, mimicking Obamacare's Medicare expansion but reducing the age limits each year as form of expansion (similar to Warren's first year proposal to reduce the qualifying age but continued).
I think on the left maybe we've taken for granted that some of this stuff is just assumed to be understood because of how many times it's been discussed in lefty circles; whereas when you get to the broader public, there hasn't been any discussion whatsoever.
But it feels unfair to say that Bernie's plans haven't faced scrutiny when every attack on Warren has paired her with Bernie. The scrutiny she faced when she dropped a plan of Public Option -> M4A is heavy for sure. But the same thing happened to Harris and Buttigeig when they shifted. EDIT: Quick clarification, when I say they shifted, I mean all three released M4A plans that had large differences from the 2016 Bernie plan that we figured everyone was basing their ideas off of. Not drawing a one to one comparison of any of their plans, of which Warren's is clearly much better.
The other scrutiny she's faced from the left at least has been on Foreign Policy where I think it's fair to say she could be better and on means testing vs universal programs (another staple of lefty conversations).