What tactical motif is this?


As usual, there are many tactical themes that could describe the position. Obvious would be that ...cxd3 is no good as the pawn is pinned due to Qxc7.
However, I think the best way to describe what I think you are asking about is something called "Zwischenzug" (German word) or "Intermezzo" (Italian word). Both of these terms describe an "in-between move."
In this position, the Queen steps out of the pin while the Rook needs to move (black was threatening ...cxd3 removing the defender of the Rook when a recapture on d3 would hang the e1 Rook with check), but then the black pieces can safely capture the d3 piece as the Queen is no longer x-rayed through the c4 square.

Thanks!
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