Worth noting that the "escape hatch" clauses in the EUPL that allow converting it into other licenses mean it's only ever as strong as the weakest license it names for such an operation, AKA EPL/MPL/LGPL.

Any actor that wants to mess around with providing a closed extension on a network service can exercise that option with an EUPL codebase, so if you care about that, you're better off explicitly naming the AGPL or whatnot.

EUPL is built for government agencies first, and most of the focus is ensuring that nobody has to worry about mix-and-matching it with other copyleft licenses, plus legal language that covers and harmonizes variations in notions of copyright/patents/intellectual property across EU countries, not so much waging war against hyperscalers. (But it's still great to have around!)