The shape of the upper tangent arc is related to the sun's altitude angle. As the sun gets lower, the sides of the upper tangent arc become higher and higher like wings. This picture is the upper tangent arc and sun dog when the sun altitude angle is about 5 degrees. This is the first time I've seen an upper tangent arc with such tall side wings. The small picture on the upper right as a comparison is a simulated picture when the sun's altitude angle is 5 degrees.

iPhone 13 Pro

Use FastStone Image Viewer to slightly adjust the saturation and contrast of the photo.
Source of simulation diagram: https://atoptics.co.uk/halo/colsolat.htm#