This exactly. As I have written in many comments before, a large set of people have such IP issues from their employment contracts without even realizing that they "too" have such issues. From the discussions that resulted in those comments, my understanding is that unless you find your case to be otherwise, if you are working for someone else in the tech sector, by default you are under an employment contract that prevents you from having side-projects of your own. This seems to vary between countries somewhat. If you have not even read your contract, or were not even aware that you signed one, please do not retaliate before actually confirming your case.

If someone has side projects on Github, it may reveal something (good or bad) about their coding skills [1], but it also reveals, most probably, their lack of understanding of legal and IP issues [1]. (It may in principle be telling about their risk-thresholds if they were aware of the legal issues and still took the risk, but this is not the most probable case.)

In various discussions I have had on the topic, even companies who otherwise are open to their employees having side projects nevertheless block them from the same in their employment contracts. In other words, if it all goes well for the company, it's fine, but if things go wrong, the employee may be under a big trouble.

[1] While telling nothing on this front, good or bad, about the same for people without such side projects on Github or elsewhere.