Usually a competitor would disguise themselves but in any case, you're a publicly accessible service, if you're doing something right you should assume competitors are going to take a peek.
Maybe you too should take a look at what they are doing, but otherwise keep "keeping on".
I'm 15 and building an edtech product with my friends, and we noticed 2 employees from a very big edtech company (direct competitor) signed up (with company email addresses) and tested some features out. I don't know if my site will ever be anything more than a hobby project, but the fact that two employees of the site that inspired my own signed up makes me feel like we might be doing something right! I just wonder how they found it.
Understanding the market landscape and competition is a top priority for any startup. That doesn’t mean you should be mimicking your competitors or trying to clone what others are doing, but you must be aware what others are doing in your space.