Render periodically runs zero-downtime maintenance to ensure platform reliability

1

Once a time I see such message in Web Service Events logs:

Render periodically runs zero-downtime maintenance to ensure platform reliability.

I wonder when this happens?
I can see it 3 days, 12 days or 30 days after last deploy.

There is no information about it in docs

3

There is no schedule for these events, they are performed as-needed.