Door Camera complaint

I live in an apartment building, and yesterday we received a call from the concierge informing us that our direct neighbor (the one facing our entrance door) complained about her privacy being violated because I installed a small door camera at the top of my door to see who is knocking or ringing.

It doesn’t record anything; it’s simply to check who is at our door. So, I was wondering if this is a general rule in residential buildings or if she’s just doing this to annoy us.

Because honestly, I couldn’t care less about her shenanigans.

Edit: I checked some legal stuff in Japan and indeed she was right, so I took it off.

Thanks for you comments and for not being judgmental at all.