Yeah it's historically accurate to blame women for everything, unfortunately. But from the characters we know in the book/webtoon, her father is actually the only one blaming her. The others just feel really bad and sad for her and Riftan believes this is all his fault so her father is just being an a**hole (as always). And most of society believes that she made a horrible sacrifice to save hundreds of people (and maybe the kingdom) so she's a hero in their eyes
So, this is something the novels go into more than the webcomic has and perhaps it's the fault of the webcomic version for omitting that content at the beginning. Nobles don't want to marry into families that are viewed as potentially being defective because then that means the child born of that marriage might then have a disability they bring into your family, and other nobles might then look at your family as being the one with defective genes. At the beginning of the first novel, it lays out that as being the reason her father abhorred her and her stutter. It could ruin their family and keep other noble houses from considering her sister Rosetta as a good marriage candidate.
Their family is already under scrutiny in that regard because after giving birth to her, Maxi's mother suffered repeated miscarriages until she died. Her father remarried to one of her mother's cousins (in his determination to get that old imperial bloodline in his family), and had the same situation of his wife giving birth to a daughter then dying before she could give him a son. That family then refused to let him marry another from their house after that because they believed any woman they let him wed would ultimately suffer the same fate. So the nobility already knows both Maxi and Rosetta's mothers had repeated miscarriages that eventually killed them, which lays out the possibility her and Rosetta could be the same. They at least have the benefit that their mothers succeeded in their first pregnancies so it's not guaranteed, but Maxi now having a miscarriage, albeit one caused by external factors, raises that question again of whether Rosetta can have kids. Everyone that interacts with Maxi knows what the cause of the miscarriage was, but her father still looks at the simple fact it happened and how it's affecting Rosetta chances.

Why are they blaming maxi for losing the child and questioning if she has issues conceiving??? Like did the emperor not hear that she risked her life to save everybody? Like if she didn’t do that the monsters would’ve overtaken the castle and probably woukdve attacked the capital