I'm using MediaWiki 1.33.1 and many images on my wiki's articles are displayed incorrectly when opened in MediaViewer. They either get stretched really wide or the height of the image doesn't resize properly to fit the box. I get the issue in FireFox and Chrome and other users have also reported it.

Here are some examples:

https://jojowiki.com/Josuke_Higashikata_(JoJolion)/Gallery (majority of the Ultra Jump covers)
https://jojowiki.com/Jotaro_Kujo/Gallery#Anime (pretty much all of the anime images here)

However, if you go to the file page itself and open the image in media viewer, they display correctly: https://jojowiki.com/File:JotaroStandCard.png