My favourite bug there (unless it's actually a feature?) when people post links reddit will intentionally break urls by actually inserting "/" in the link url especially if the urls have "_" to separate words in it. so this_is_an_example becomes this/_is/_an/_example.
When you use their "app" it works, but if you use a browser it breaks.
As far as I know, that's because way back when they introduced "new Reddit" (the redesigned web UI) they made the bizarre decision to use a slightly different and incompatible Markdown parser. So ever since then, posts and comments have looked different depending on which version of the site you view them on.
The URL escaping syntax is one difference, but another one is that the two renderers support different syntax for monospaced code blocks. As you can probably imagine, that wreaks havoc on the formatting of posts in programming subreddits.
This is definitely a feature. It's intrusive, obvious, and has been around for a long time. It creates friction for users of old reddit with plausible deniability.
When you use their "app" it works, but if you use a browser it breaks.