I think I have heard of it, but forgot it. But that could be deja vu.

I don’t think it is necessarily the case that the Vickrey auction will produce a higher final price. How people will react is not entirely predictable, nor is the pool of people and their minimum bids.

For example, in the case where there is a significant gap in the amounts the two highest bidders are willing to bid, the Vickrey auction could produce a lower amount paid.

But it seems to me that the clearest reason why Vickrey auctions might tend to produce more, is what you wrote in your question: in a non-Vickrey sealed auction, bidders may tend to not bid the most that they’re willing to pay. Various things may enter their imaginations as they do so, but they’re guessing what they might get it for, what others might bid, and/or they may be second-guessing what others will be bidding using similar mindsets. Also, some people may dread paying more than they could have, in theory. Vickrey encourages bidding the actual highest amount one is willing to pay.

Yes. I remember reading that it tended to fetch the highest prices for items, but I can’t remember the circumstances around that conclusion.