That's a bit different. This is about the XUL box model specifically.
What Zotero 7 will continue to support for plugins is full access to the Mozilla platform internals, unlike WebExtensions, but Zotero 7 is based on Firefox 102 ESR and will be updated to 115 ESR later, so platform changes like this do apply. The reason all plugins have to be updated for Zotero 7 is the massive architectural changes in Firefox over the last few years, most notably removal of XUL overlays. This change might require some minor additional updates, but it's probably not a big deal.
What Zotero 7 will continue to support for plugins is full access to the Mozilla platform internals, unlike WebExtensions, but Zotero 7 is based on Firefox 102 ESR and will be updated to 115 ESR later, so platform changes like this do apply. The reason all plugins have to be updated for Zotero 7 is the massive architectural changes in Firefox over the last few years, most notably removal of XUL overlays. This change might require some minor additional updates, but it's probably not a big deal.
(Zotero dev)