Please be advised that an OpenEXR side-tag update  is on its way for
F35 (there was an older update that has been unpushed because the
side-tag it's expired during the beta freeze).
I tried to rebuild kf5-kimageformats in the side-tag before realizing
that it is being updated in a kf5 side-tag itself... so, before pushing
the kf5 side-tag into an update, please look if the OpenEXR update has
already been pushed to stable or if a buildroot override is needed to
build kf5-kimageformats against the newer OpenEXR.