Cannot cancel iMovie export

Some times I notice a mistake in a video that I've already started exporting. If the video is large and the export is going to take a long time (2+ hours), I would like to be able to cancel the export. Previous versions of iMovie had an "x" in the upper right corner of the progress window. I never see that in the progress window anymore. All I see is the estimated completion time. That means I have no choice but to let the export finish. How can I cancel an export when the "x" doesn't show up? I don't like the idea of doing a "Force Quit", not knowing if it could leave the video's data corrupted. I'm running iMovie 10.4.3 on MacOS Sequoia 15.4 (24E248).