Got an answer to my question for the logs from the admin (@Milan) of the instance. But sadly he can’t help here. So I think it will be as mysterios as it was.
sorry for the bad news. @rretsiem if you know the social.tchncs.de admin(s), feel free to ask them for any related server logs from around this time, 2020-03-24 10:46:23 UTC, they might be able to help!