Would you consider my half sister and half brother’s relationship incest?

My parents are divorce and currently is married to different people. My father has a daughter with his new wife and my mother has a son with her new husband.

Both are my half blood siblings. However they started dating and are in a relationship with each other. Both does not share a parent with each other or any form of blood relation except for the fact I am both their half sister. Is this consider incest?
Would you consider my half sister and half brother’s relationship incest?
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