Jira allowed you to attach an image file, and then you could embed the image inline with your text in the issue description
Example with Jira
Same with YouTrack
Youtrack doesn't seem to handle alot of Jira's wiki syntax. I can see that YouTrack uses different syntax for header/titles, which is OK but incompatible.
Youtrack is missing these key features:
1) embed attached or url images in text