As someone who uses Nextcloud, why do you suggest obfuscating the name of the calendar event? My nextcloud instance is only accessible from outside my LAN via HTTPS, so no concern about someone using a packet sniffer on public WiFi or something of that sort. The server is located on my property, so physical security isn't a real concern unless someone breaks in with a USB drive or physically removes the server from the rack and steals it. If someone was to gain access to my network remotely, they'd still need login credentials for Nextcloud or for Proxmox in order to clone the VM drive.

To be clear, I'm not disagreeing with you; I'm wondering if I may be over-estimating data security on my home network. Considering you're posting from infosec.pub, I'm assuming you know more about this than I do.

Also, I feel like I need to say that the fact that OP even needs to consider data security for something like really makes me wonder how parts of our society have gone so wrong.