I interviewed with a company. Naturally they asked for my side projects which I showed them. We talked about technical challenges, scaling, interesting bits of codes - all these kind of things. They were really excited. I passed the interviews and got the job.
Fast forward a couple month, still working on my side projects, some of which started generating a couple hundred bucks a month. My boss started asking me to stop any side projects and put all my time thinking about the company instead. I refused and said that I am 100% there during my work hours but what I do in my private time is not related and even the reason why I got this job in the first place. My boss didn't like that at all and even tried to figure the exact times out when I would work on private stuff to hold it against me. I eventually quit.
If your company wants to see side projects but dislikes the idea of you actually working on them after starting, you are doing something wrong.