[asbell]

Can anyone explain why the bot throws the ♥10 instead of one of its useless small spades?

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[pescetom]

I suspect part of the explanation will be that it was hopelessly confused by the weak NT opening (maybe it imagines Declarer holding clubs KJ and is fearful of being thrown in with hearts after cashing spades AQ).

[Huibertus]

Bots calculate scenarios and pick the defense that scores best in most scenarios on average.

Declarer's actual hand was NOT part of the calculation. She opened a 15-17 NT the bots assumed she held 15-17 HCP, not 12 HCP.

The bot KNOWS declarer held ♦K not more in ♦, ♥K not more in ♥, ♠AQ not more in ♠ (as inferred by the ♠ finesse).

So the bot calculates declarer must hold ♣ K or KJ for 15 HCP. The scenarios it sees is discarding a ♠ will lead to declarer cashing ♠ winners and throwing the bot in with another ♥ lead to be forced to bring declarer ♣ K as declarers 10th trick, as compared to you holding ♥ 87XX gaining the lead instead of itself to hold declarer to 9 tricks only finessing declarers assumed by calculation King of ♣ after making ♥ 7.

So it is actually real GOOD defense. You both got fooled by the west player opening 1NT on 12 HCP.

It's close to undoable as you are protecting a potential ♠ stopper, but had you been aware of what declarer opened 1NT on you should have held on to ♥8.