Lemmy being pinged each midnight

[removerpuzzlehunchback@lemmy.world]

Hi all,
I selfhost private instance of Lemmy for my friends behind Pangolin reverse proxy. I noticed something interesting in the logs; Lemmy specifically gets pinged / tried to access each midnight UTC from what looks like an IP from inside the network. Just out of curiosity, do you have any idea what that could be? I have federation off and private instance on, but maybe it is something from Lemmy network checking if my server is alive?
Thank you in advance

Update:
So it turns out I was perhaps correct with my hunch.
The local IP turns out to be the proxy I set for ports 80 and 443 (it was internal Wireguard IP).
Unfortunately my current setup did not allow me to catch which IP the request came from (which is a problem I have to solve later) but the lemmy-proxy container got requests for GET /.well-known/nodeinfo and GET /nodeinfo/2.1.
So it is probably something checking my server, likely from the Lemmy network.

Update 2: So after I disabled Pangolin for one night, after I reenabled it, the requests do not come again! So the Lemmy network must have figured out that my instance is set to private and stopped pinging.