We would like to thank Malgorzata Worek for providing us with numerical input for the study of off-shell effects. We are grateful to Giuseppe Bevilacqua for further clarifications and to Andre Hoang, Katerina Lipka, Marcel Vos, and Sebastian Wuchterl for useful discussions.
The work of S.A. and A.G. is supported by the ERC Starting Grant REINVENT-714788. S.A. also acknowledges funding from Fondazione Cariplo and Regione Lombardia, grant 2017-2070 and from MIUR through the FARE grant R18ZRBEAFC. J.F. and A.I. acknowledge support from projects PGC2018-094856-B-100 (MICINN/FEDER), PROMETEO-2018/060 and CIDEGENT/2020/21 (Generalitat Valenciana), and the iLINK grant LINKB20065 (CSIC). The work of M.V.G., S.M. and P.U. was supported in part by the Bundesministerium für Bildung and Forschung under contracts 05H21GUCCA and 05H18KHCA1.