One important question for determining how bad this is: What sort of mistreatment are we talking about? I remember talking with a colleague who used to work at Electronic Arts, and what he said about how stressful it was and the awful hours; you could certainly call that mistreatment or abuse. That was back when I was an intern, and was perhaps a formative experience in steering me away from pursuing jobs in the video game industry.
Put another way, more information is needed to determine if this is Blizzard level, EA level, or something else. Based on the insufficient information we have here, I'd guess a mix - the fact that a significant amount of the men at Paradox reported mistreatment or abuse suggests that general working conditions are a significant problem, and the fact that a significantly larger amount of women reported abuse suggests there is sexual discrimination going on - which may also include harassment.
If it is Blizzard-level, I'll be curious what other studios provide decent grand strategy games. Civ really does not qualify. Maybe some of the Slitherine/AGEOD ones that I haven't really explored? Old World is definitely on my list, and I was already much more likely to buy it than CKIII. Possibly Anno 1800 instead of Victoria, but is Ubisoft any better? I've avoided them for a decade, other than their GOG back catalog, due to their DRM stance. And CD Projekt, for that matter, isn't fully in the clear themselves, with their Cyberpunk 2077 crunch last fall.
Regardless, it is unfortunate, and will be interesting to see what emerges. Perhaps even more interesting to read the more detailed stories that emerge over the years - was this always a problem, or were there events that made things worse? I've worked at a company that was a pretty great place to work, and pretty good at supporting women in IT, particularly women new to being in the IT field, until it got acquired by a big public company that had a big PR machine but didn't know how to treat people as people instead of cogs in a machine. But in that case the mistreatment was both non-discriminatory, and also somewhat random (some projects had management that mistreated employees, while others were fine). So while the report is entirely believable, I'd like to know more details before I write off Paradox in general. What type of mistreatment, is it a general problem or concentrated in a few studios, etc.