Don't call if_deactivate() in bridge_clone_destroy(). Following if_detach() will do this.
Index: sys/net/if_bridge.c =================================================================== RCS file: /cvs/src/sys/net/if_bridge.c,v retrieving revision 1.345 diff -u -p -r1.345 if_bridge.c --- sys/net/if_bridge.c 6 Aug 2020 19:47:44 -0000 1.345 +++ sys/net/if_bridge.c 1 Jan 2021 22:33:42 -0000 @@ -237,9 +237,6 @@ bridge_clone_destroy(struct ifnet *ifp) bstp_destroy(sc->sc_stp); - /* Undo pseudo-driver changes. */ - if_deactivate(ifp); - if_detach(ifp); free(sc, M_DEVBUF, sizeof *sc);