Defensive coups in the trump suit

Recently, my partner Ethan Wood and I were the hapless victims of a clever defensive play by Andy Goodman, playing with Chris Compton:

The scene was the "Social Distancing Pairs," a side game in the first online regional tournament set up by the ACBL. We got to a good contract, 3♠ by South. Follow the play. At trick 4, Ethan took the percentage trump finesse (to the T9). Knowing that he was only "entitled" to one trump trick anyway, Andy realized that a little subterfuge might just get him two--and, more importantly perhaps--upset the timing of the whole hand. So, he won with the K, exiting with a heart (all the better to have the "winning" trump finesse taken a second time). Ethan played another spade towards his hand. When Chris followed low, there was still the J and 6 out against him. The jack was of course "known" to be in the East hand. Playing the T would "obviously" allow him to pick up the suit, whereas playing the queen (if he foresaw a problem) would in any case necessitate another finesse which, admittedly, could probably be achieved successfully assuming Chris had three hearts.

But, seriously, who in their right mind would play the queen (or ace) here?

Of course, Andy now disrupted the whole hand by putting Ethan again in dummy where a diamond could no longer be finessed. The result? 98% for them, 2% for us.

My own play in a friendly team match a couple of days ago was less spectacular but equally effective. Playing a team game with friends (I've made the players anonymous), I was faced with the situation of what looked like a cold contract by my RHO. In fact, he's making six. What could I do to disrupt things? Follow the play:

Again, declarer did something entirely normal. He could have made the contract with two overtricks at any time after my duck. When I did win the trump queen, the contract was still cold but I think declarer probably credited me with having started with Q972 in which case, he might end up down 2 if I had a fourth heart. I think what happened is that declarer was now off balance and, while he could have steadied himself by drawing both the last trumps, it can be hard to recover when all your earlier assumptions have been invalidated.

BTW, both sides missed 7NT on this hand but our teammates were in a safe 3NT for an 11 IMP gain.