throwaway642012

I'm a freelancer in Germany, and I'm waiting for the new project to be finalised. Meanwhile I'm working on a ML based app, and a startup approached me to do some hourly work. The startups is in the same space as my product, and is similar in some ways to my app. We've not signed a contract as I'm planning to work only 10-16 hours for the startup. I've not yet started the work (for the startup) yet.

Will there be potential conflict of interest/ legal issues in the future if I launch my product?

Should I take some steps to indemnify me from the other startup?

Any help is highly appreciated.