Would it be possible to put the list of updates into a vertically scrolling element, and then limit the height of the dialog box to something sensible?
This morning, on macOS, the dialog was so tall I could not access the button to dismiss it and had to force quit Joplin, then download and install the latest update from the website, before I could use Joplin again.
What version of macOS was it?
For me it displays the dialog with a scrollbar so there's no issues:
