Unusual circular reflections on our windows before sunset

[Ulla]

How did you find PF?: Via Google search using key words: sun, window, circular, pattern

We were outside raking in the afternoon November 4, 2024 when we noticed an unusual circular pattern on the windows. It was around 3:50 in the afternoon. The sun was visible between layers of clouds. We have lived in this house for 37 years and working in the backyard this time every year but never noticed anything like this before.
The windows are Anderson double pane. I would love to know what caused this. Thank you!

 

[Ibix]

See this thread. Your windows aren't quite flat, in short, so you're seeing a distorted reflection of the sun and probably illuminated clouds.