Not sure if any of these spawn a powershell window but I can see amazon has an agent running regularly, tailscale is flushing dns regularly. I guess if I did the same in an azure server I'd see some other variations.
Here's what i found. I mean it sounds legit. certbot is asking powershell to do a renew (if needed) twice per day. And for a moment, the blue powershell window pops onto the screen and disappears. A bit unnerving i would suspect for some folk. it is supposed to be hidden as i see in it's common line, but it isn't.
It might have been a coincidental non related bug, but powershell was firing off maybe not every 20 minutes, but certainly once per hour. maybe I was rebooting a lot while trying to figure it out, maybe that caused the event to re-trigger? Anyhow, sorry about raising the alarm like that, I'm new at this, and was a little stressed and confused, but thanks to your clear documentation, I managed to get it working, at least i'm fairly sure. it seems to trigger maybe twice per day now.