Strange sharing request in Apple Fitness

Something very strange just happened on my iPhone. I received a notification that some stranger started sharing their fitness activity with me. Said stranger was posting with my dad’s name but a completely random gmail email address. I know for a fact that this person was not my father, for one because he doesn’t even have an iPhone.

Anyway, the strange part is that I was not asked whether or not I wanted to accept this data. I was simply notified about the fact that this stranger had started sharing their activity with me. To make matters worse when I went to Apple Fitness and opened the sharing tab to investigate I realized that this stranger was now listed in the “Sharing With” menu. In other words: I was never asked whether or not I wanted to receive this data or share my data with them. It just happened, and some random stranger was able to view my fitness data to which I never consented.

I don’t use that sharing feature. I never have. In fact I find the idea itself utterly revolting. However, I can’t find a way to disable it entirely, unfortunately. Is that true?

Does anyone know what the heck happened here?