Text:
I consent to Plex to: (i) sell certain personal information (hashed emails, advertising identifiers) to third-parties for advertising and marketing purposes; and (ii) store and/or access certain personal information (advertising identifiers, IP address, content being watched) on my device(s) and share that information with Plex’s advertising partners. This data is used to deliver personalised ads and content, ad and content measurement, audience insights and product development. Your consent applies to all devices on which you have Plex installed. You can withdraw your consent at any time in Account Settings or using this page.
Soure: https://www.plex.tv/vendors/ (Might have to clear cache)
Can also read about the changes here: https://www.plex.tv/about/privacy-legal/
Jellyfin is a fully self hosted drop in. That means it's up to the server operator to handle everything. You would still tell your mom to just install the Jellyfin app on her TV with the one additional step in your server address which you would tell her.
But yes, you as the operator have to do some extra things like implementating a reverse proxy and if hosting out of your home make necessary network configuration changes to accommodate this access.
You as server operator also have to check what device your mom has and point her to what app download, because Jellyfin doesn't have an app for everything
True though that's less server operator and more "just being helpful to your mom". That said it seems nowadays that a Jellyfin app is available on most devices/ecosystems (or maybe I just don't have experience with enough devices to have an accurate idea).