Why was my move so bad?

I'm playing black pieces and on my move the computer eval goes from -4.9 to -0.6 but I don't even see how their suggested move is better by more than a minor piece value. Maybe it's a long tactic outside my horizon like an eight move tactic?

Idk but 17. ...Bxd2 seems to resolve all difficulties white is having. I would call it more a positional advantage than a tactical thing, and it can be difficult to maintain and turn in to a win. White can't castle and overall his game difficult to develop. But that's just my superficial feeling of the position..

So what is the suggested move? (fer cryin out loud)

"The threat is stronger than the execution."

Sorry I didn't say the suggested move, it's queen to d3.

Probably Qd3 is more annoying for white. Sometimes engines are picky about moves that humans don't get.

you had white on the old rack, a few more turns of the screws ,,,,,,, but then you released the tension allowing white to castle bringing his rook into play, you really do not need to look deep to see that ,sometimes you can't see the woods for the trees maybe less calculating and more thinking of a plan or strategy .
Anyway that 's my take for what it is worth, lols