This is not theme-related or even a bug: it’s a security feature.
WordPress only allows a few HTML tags and attributes in comments, and the img tag is not one of them. You can find the list here.
Your screenshot is likely coming from a commend you edited in the dashboard.
If you, the administrator authored the comment, you can add the img tag and it should NOT be stripped out. The image should be displayed in the comment.
But if you edit a comment previously authored by a user without the unfiltered HTML capability, any tag the original author is not allowed to use will be stripped out.
Of course, this is WordPress and open-source: so you’re more than welcome to override the global allowed HTML tags. See the suggested code snipped in this thread: https://www.ads-software.com/support/topic/not-possible-to-post-images-in-comments/
