Yeah, lol, that's the thing; if you make it so people can't solve it then they'll complain not everything was there for them to work it out and if they solve it then it wasn't a good mystery and it was too obvious. Can't win with mysteries, honestly.
I don't care about mysteries that the reader themself can't solve IF the mystery is not the main point of the work and is instead just around what everything else is centered. I rarely try to figure out the mystery itself, I more often like just seeing what happens.
People have very wide criteria for what constitutes a good mystery so it's hard to satisfy everyone.