I didn't know that. I self host this on my own hardware in my office. If I wanted encryption at rest, I would just do it at the hard disk level I suppose.
I also self-host NextCloud, and if we're honest, its image hosting is pretty underwhelming in comparison. I moved it to Immich. If those issues are critical to you, however, that is a valid concern, but I'd venture to say they aren't critical to most self-hosters, whereas good mobile sync, AI integration (intelligent search and facial recognition), and ease of use are. Immich excels at all three.