Very cool idea, and very well implemented. My only feedback is that you should clarify whether the solution has to be a valid position that can be reached in a chess game.
It's really confusing to me that I drag a piece, I drop it on a square, it stays there, and there's an animation that the piece returns to the bottom. If it stays there, it shouldn't have a "returning" animation. Otherwise, it's an interesting puzzle.
Managed to guess it on the first try after realising it looked like a real game. Bit sad to see only one puzzle per day.
Sharing the result also reveils the solution in copied text, maybe remove that so someone could share the exact puzzle without immediatly seeing the solution.
At first I thought it would be the typical chess exercise question, just that everybody gets the same one each day, but I like the approach you have. Makes one think differently than usual.
at least on the first one there was really only one way it could have happened under reasonable assumptions (mainly, that the white queen had just been taken). I'm not sure it works very well for the Wordle format, although it is fun as a puzzle otherwise.
Here is mine: https://www.solitairle.com/
Sharing the result also reveils the solution in copied text, maybe remove that so someone could share the exact puzzle without immediatly seeing the solution.
https://youtu.be/_Ntn4jEv7rE?feature=shared
Very cool to have to think in the other direction to solve it.