the overall premise of the show ponders what it means to truly be "you", and the different versions of ourselves we portray in different environments. the topic is regularly discussed in-universe as well.
a character leaves her baby under the watch of someone she wholeheartedly believes she can trust. the one watching the baby leaves the house without the baby, and the mother is shown screaming and panicking when she realizes her baby can't be found. shortly afterwards, the baby is found perfectly safe in a spare bedroom. not necessarily "abandonment", but still worth mentioning.
A villainous character is beaten to death with a bat early in episode 7. We see the first swing at their head, hear the others, and then see a heavy trail of blood as the body is dragged away.
No but there is a scene in episode 5 where irv looks at mark while black goo drips from the ceiling and there is black goo coming from one of marks eyes
a character attempts hanging themselves with an extension cord. they're shown kicking and flailing while choking at the end of the episode and at the beginning of the next. they're saved from dying, but they have visible bruises on their neck for a while afterwards.
Multiple occurrences. The act of severance also basically means that a person has two identities, and one is no longer conscious whenever the other is activated.
Autism/ABA is not the subject matter, but several scenes and the general premise heavily feature infantilization, reward structures, punishments, and forced expectation that several characters perform their work duties without question without understanding what they do, which may closely parallel ABA-related traumas
Content warnings are provided onscreen beforehand for the episodes where flashing is present, but those warnings are there for actually most of them. I personally didn't find any of it very extreme — I didn't even notice it most of the time, I couldn't tell you where the flashing was in half the episodes that had warnings — but I'm not especially photosensitive.
The founding family of the company most of the characters work for is portrayed to have founded an organized religion/cult and entrapped their employees in it, with characters having varied relationships to this religion ranging from rejection and entrapment, to fanatic devotion. Religious texts and painted imagery associated with this religion are seen and quoted frequently, and evoke imagery from real world religions. No real-world religions are explicitly portrayed aside from some minor christian imagery, and exclamations like "Jesus Christ."
Two characters are seen briefly in bed together after sex (towards the end of episode 6) and there's a rather disturbing scene with suggestive outfits and dancing (2/3 through episode 8), but there is no explicit sex. Not a lot of references to it, either.
the whole premise of the show does heavily rely on people temporarily forgetting large parts of their memories (not caused by dementia/Alzheimer) though, so i could see how it could be triggering
at the time of writing, there's only been one season, so there isn't really an ending yet, but season one's finale ends with a lot of ambiguity and mixed emotions.