the app died for three weeks and then everyone came back at once

Genuinely curious whether anyone else sees this or if I have invented a weather system.

For about three weeks in January this thing was dead. Not slow. Dead. No likes, no messages, and the feed refreshing to the same faces I had already seen. I assumed I had done something, changed a photo, said something wrong, been quietly demoted by whatever the app uses to decide who sees you.

Then last Sunday evening it was like someone opened a door. Four likes in an hour. Two messages, both from people who had clearly read the profile. Feed full of people I had never seen. Nothing about me had changed at all, I had not touched the account in a fortnight.

So which is it. Is there a real rhythm to when people are on these things, holidays and weather and Sunday nights, or is this just what a small pool looks like from the inside and I am doing astrology at it?