Fit-Dirt7981's journey

I recently resigned from my position at a tech company, where I was working as a software engineer. On the same day I announced my departure, I informed my senior VP that I would be joining a competitor. Shortly after, I was told to return my company laptop and badge, which I did. I took this as an indication that I would be on garden leave for the remainder of my notice period. However, a few days later, I heard from HR that they were discussing whether I could still do any non-confidential work during my notice period. This has left me confused and concerned. My main question is whether my employer can actually require me to come back to work after they explicitly told me I was no longer supposed to work and took away my access to company resources. I’m also wondering if the fact that I mentioned I was going to a competitor changes the situation. I’m based in Germany, and I haven’t received any formal communication from HR yet; I only know about this discussion internally. Has anyone else experienced something similar? Is this typical for a situation like mine, or could they really change their mind and require me to work again?