I've never heard anyone complain about it, tbh.

The menu functions of a DVD are meant to work with the firmware of DVD players, which is a function Jellyfin doesn't really cover.

The usual to-do is just have commentary tracks ripped and placed in the same spot as other language tracks, and bonus features placed in folders alongside the original video.

I don't know the answer to your question, though I suspect it's that Jellyfin doesn't support menus.

What I've always done is rip each track to a video file. Jellyfin's movie metadata DOES support extras: https://jellyfin.org/docs/general/server/media/movies/ and video formats like mkv support additional audio and subtitle tracks. With multi-track video format and extras support in the Jellyfin native menus... it's possible to rip the vast majority of DVD content into Jellyfin. But ISO is not the preferred format to do it.

The main thing you'd lose here would be interactive menu features or choose-your-own adventure video codes into menus. Those DVD titles are pretty rare though.

VLC might have DVD menu support for ISOs, fwiw. I have a vague recollection it might, but I'm not at all sure.

I'm surprised it plays .isos at all, that's pretty cool. I thought you'd have to rip it and then put special features you want to have into an Extras folder.

Edit: welp, other comment thinks this as well so it seems the way to go (but lots of work, obviously).