Avoidable Rectangle Type 1
Digits you placed fill three corners of a rectangle. Completing it would give two solutions, so that digit goes from the fourth cell.
How it works on this board
Assuming the target lets the highlighted pattern swap into a second solution
1
9
7
3
4
2
8
6
5
2
6
9
8
7
3
8
3
6
7
9
7
3
6
6
5
3
9
3
2
6
9
4
5
8
3
9
5
1
4
6
6
2
9
1
5
3
1
3
6
8
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