See https://musicbrainz.org/release-group/f404bde6-0cf0-45ff-a481-381886b28593 for example.

In essence, with a very long URL (in this case for Wikipedia - but I guess it could be any URL), the Right Hand column expands to fit the URL, squashing the main panel.

The fix is to change the CSS for the "a" tag in common.css to add "word-break: keep-all;".