Ok I used trigonometry to calculate the new extent. Formulas work! Thank you so much for clarifying.

Ok so it is the smallest bounding box of the image in that case, that seems reasonable. So I will need to manually resize the image to fit in the original bounding box for which I will need to scale the image back. The next question that arises is how do I know the bounding box before applying a transform? I will need that to calculate the scaling factor.

Yes, I noticed it yesterday!

This feature is completely broken in iOS 15 betas(including beta 5). I have filed a bug FB9393169 but there is no response so far.