I tried to find an unbiased answer to this so I looked at the global rising page as an anonymous user. The majority of submissions are about web development and related topics (e.g. mobile development) as well as JavaScript in general. So this is not just my filter bubble: your assessment seems correct.
But don't let that discourage you: it's probably a good thing to have more diverse topics on Hashnode and there is a lot people in different parts of the field can learn from each other. Heck, most of the ideas that are currently hot and trending originally showed up in different areas decades before.