Ask HN: Should I tell the HR that I recently joined a company

I recently got an offer from a company and I am joining them from next week, before that I was a freelance dev.

However, I have an upcoming HR interview with a German company this week. This opportunity is better than my current company. I am not sure whether to tell the HR about my new company or not, I don't want to be perceived as a job hopper.

Should I mention about my new job to HR or just tell them that I am still working as a freelance dev?