Interesting question, and one that has changed since the Golden Age of Agatha Christie and others.
I raise the issue on reading WILD CHAMBER by Christopher Fowler. One of the characters in this baffling plot defines the whodunit, then goes on to list what should nowadays be forbidden. I quote:

• “A murder mystery is an intellectual exercise, a game between reader and writer in which a problem is precisely stated, elaborately described and surprisingly solved.
• “The traditional rules of fair play demand that the criminal must be someone we’ve met. There can be no supernatural elements, no secret passages, no imaginary poisons, no Chinamen, no twins, no mystical intuitive powers, and the detective himself can’t have done it.
• “To them I would add several further moratoria: no more alcoholic policemen with dead wives, no autistic idiot-savant crime scene specialists, no oppressed female detectives derided by sexist colleagues, no overweight computer nerds in dimly lit rooms, no erudite killers arranging corpses in tableaux reminiscent of medieval paintings, no renegade detectives sharing a psychic bond with the killer, no cryptic messages hidden in museums by victims, no opera-loving loners who solve crimes because without them their lives would have no meaning, and absolutely no more reinventions of Sherlock Bloody Holmes.”

Strictly followed, this no-no list would eliminate most of the whodunits I have read. It is rare indeed for a reader to discover total originality in crime fiction. Which is why the rare authors who achieve it are global favourites.

PS – try Ann Morven. https://www.smashwords.com/books/search?query=ann+morven

Happy reading! from Ca