When I think about it, alt text should provide name of the person, if that is relevant for the image. Something like, "John Smith behind a desk in his office" and not "A Person sitting behind a desk". Sighted people may or may not recognize a person, but blind people simply can't see it.

Erm... isn't alt text supposed to be used as an alternative to image, not as additional info about it?

Obsidian writes (or was doing so when I did a research and testing, about a year ago) to disk with almost every key pressed. That creates issues if you have notes in folder shared with tools like Dropbox or MEGA. In the end, I have decided to use Logseq. :)