When you have a release which has a large number of Other Versions in the Release Group they display very poorly.

Pop-up is very wide - probably trying to be multi-column but only one column is shown.
Pop-up takes whole height of screen - needs some margin at top
Pop-up could do with border and feint grid lines to aid with readability
Full list is not displayed - pop-up needs a vertical scroll bar and scroll arrows at top/bottom.

Examples:
Release: https://musicbrainz.org/release/17a3277d-59f1-370b-87c9-69b43666d5d2 35 releases in release group, pop-up is double single column width
Release: https://musicbrainz.org/release/c0f74d5a-7534-414d-8b90-0ebe6c5da19e 62 release in release group, pop-up is possibly triple width