Thank you again for your suggestion.
And (as you already knew -- and now I do too!) you are correct. The Jellyfin server no longer crashes when trying to shuffle all my tracks (~20,000).
And when I view my music by "Songs", I can shuffle all the tracks without issue while using the web interface via Firefox. Hooray! I never got that far with jellyfin before.
Unfortunately, the Roku jellyfin client (again, this is my use case) doesn't have a view by "songs" option. As such, in order to shuffle all my tracks, I needed use a playlist (an actual m3u playlist rather than a jellyfin playlist -- as I don't really want to have to individually click on 20,000 tracks and add them to a jellyfin playlist -- which might or might not work anyway).
Which isn't a big deal, as I already used such playlists elsewhere. But attempting to play or shuffle such a playlist fails. Not just on the Roku client, but on Firefox as well.
So I guess I'm either going to have to wait for jellyfin clients to support such large m3u playlists, or until the Roku client has a "Songs" view.
Again, thanks for your heads up. It was much appreciated!