@algernon@come-from.mad-scientist.club @imcdowall@mastodon.social @petrillic@hachyderm.io EUPL is an odd license, because it has strong copyleft requirements like that and then a relicensing clause which just allows you to relicense to a weaker copyleft license (like GPLv2-only, GPLv3-only, or even any version of the GNU GPL via CeCILL v2 (because it allows relicensing to CeCILL v2 which itself allows relicensing to any version of the GNU GPL)) and bypass those requirements entirely.
I'd just use the AGPL. What is actually wrong with it anyway?