Quick bookmarks question

I want to open the coordinates of the cursor position in openStreetMap. This works fine with Quick bookmarks and the predefined favourite "openStreetMap", the page opens in my default browser (Vivaldi).

However, I want openStreetMap to open in Firefox, as editing in Vivaldi is not fully functional. I don't want to set Firefox as my default browser, though.

So I select "openStreetMap" in the quick bookmarks menu and then choose Firefox as the "target application". Unfortunately, Vivaldi still opens when I use the quick bookmark.

(The URL syntax is the same; when I manually transfer or share the link in Firefox, openStreetMap opens there as desired).

What can or must I do to make my quick bookmark display the position according to osm directly in Firefox?