OpenSCAD and others look like they did even before Sequoia, with a small corner radius and older control spacing.
It looks like you can make your Qt app look like it did for previous OSes:
https://www.qt.io/blog/qt-on-macos-26-tahoe
That might be a useful stop gap.
It looks like you can make your Qt app look like it did for previous OSes:
https://www.qt.io/blog/qt-on-macos-26-tahoe
That might be a useful stop gap.