I recently used iMovie and since quit the application, but it still shows a green dot, saying iMovie is using camera

I have tried going into Settings > Privacy & Security > Camera The three items there were iMovie, Parallels Desktop, WhatsApp. I have turned all of them off. I have quit all applications aside from the web browser (to write this question). I have tried re-opening and quitting iMovie. The green dot remains, with the status as shown in the image below. I have not yet tried restarting, in particular because I would like to get to the bottom of why this green dot is on and restarting might reset whatever process is causing it. This seems to have started when I opened iMovie for the first time just a few days ago, and connected a firewire interface via firewire to thunderbolt 2 to thunderbolt 3 cables. I am not sure if that is relevant. But, maybe the act of plugging in that device somehow did something?