Comment 3 for bug 2047021

I haven't been able to reproduce the vertical layout on Windows, but it seems to have a very small width for the dialog somehow in your screenshot?
We are just using https://gnome.pages.gitlab.gnome.org/libadwaita/doc/1-latest/class.MessageDialog.html for the dialog, so don't have much control over its layout

I can reproduce the error message that appears.