I've just submitted v5.2.0 of IH-5 for the Zen Cart moderators' review; I'll post back here when it's available for download.

This release contains changes associated with the following GitHub issues:

#139: Removing (buggy) "Small Image Zoom" feature.
#229: Correct handling of missing images.
#231: Various refactorings.
#233: Correcting (PHP 8.0+) Fatal errors due to stricter typing.
#236: Removing template-module overrides; changes in zc156+ core.
#242: Removing (unused) bmz_gif_info.class.php.