I noticed a small thing in the new version, JabRef 5.0. The Web Search panel is very nice and convenient, but it doesn’t seem to have the DOI option in the scroll bar. I’m not sure if there is a reason but you can already import DOI from the Library tab so it would be nice to also have it in the Web Search panel.
The DOI fetcher has been added to the New Entry dialog.
Alternatively, you can also paste the DOI on the maintable and JabRef will fetch the entry for the doi automatically.