As much as it sounds cringe, RoN is NOT like those other games. (Insurgency, Dying Light, RDR2, CP2077, Outlast Trials, Last of Us, etc)
Ready or Not is a realistic depiction of violent police activity.
(yes, I know the word realistic might be up to debate for us, but this matters a lot when under review, RoN is NOT cartoony, it doesn't attempt to be overtly satirical, it tries to be real and simulate versions of realistic gruesome events)
RoN does not get the cover of "war", it is not a dystopian society or apocalypse, it is not a "shocker" style horror game, it is not violence against otherworldly entities/monsters or objective "evil".
-Because of this, nudity becomes a concern, when compared to something like GTAV.
-Violence becomes a concern when compared to CP2077.
-Gore becomes a concern when compared to a zombie shooter or the like.
Being able to brutalize a civilian populace in a realistic way, as a governing force, is probably what is getting them flagged at this current point in societal/censorship concerns from Microsoft, Sony, or the other governing bodies they mentioned.