the big four warnings are: noncon, underage sex, graphic violence, and major character death. which means that, even if we restrict to common topics many people are interested in exploring in a fic space, 'no archive warnings' can include:
the vast majority of politics and history
recovery from physical or sexual abuse
death of minor characters, grief as a major theme or the central topic of the story
including death of a parent, sibling, partner, child
disease, medical abuse or trauma
serious injury and slow/painful recovery or lack thereof
chronic fatigue, chronic pain, other chronic disability
serious bigotry treated seriously
serious bigotry treated like a joke
colonialism and forced assimilation, eugenics
genocide (described non-graphically)
grooming and romantic abuse of children, assuming sex is either implicit or doesn't take place until the kid turns 18
phobias, dissociation, hallucinations, unreality in such a way that can be very psychologically disorienting
horror genre and horror pastiche
workplace politics and drama, workplace harassment and abuse, capitalism basically just sucking
the most annoying people you ever met who simply won't stop talking to the main character
inaccuracy about real world information, including conspiracy theories and dangerous advice
inaccuracy about canon lore, possibly on purpose as ragebait crackfic or badfic