I noticed I have a bit of issue and I’m not sure whats causing it.
When I first open my app there is a rather big gap between the toolbar and the controls below.
The reason for this weirdness is that window properties are being adjusted (maybe after the window is initialized), if you do not have any declares or plugins, then I suspect it might be the Xojo framework setting the toolbar style to adopt the Catalina (and below) style, instead of allowing the window to use the OS specified style, which in this case is the iOS Big Sur style toolbar.