Windows did not change sizes for me either but it took longer than usual to find matching windows while trying to build a tiny home yesterday. I think the small room size combined with a lot of furniture makes 'larger' windows feel out of place. Nearly every window was next to a piece of furniture like a counter or a table so only the smallest windows seem to look good so close to the furniture, depending on the style of the house of course.
In other words their actual window size didn't change but the visual effect does. That's my personal impression at least. But perhaps changing the wall height as suggested by @Netzspannung might help.