m_inithdr() is already called a few lines above.
From my understanding, this is a duplicate and the second call can be removed.

Did I understand correctly ?

Index: if_vxlan.c
===================================================================
RCS file: /cvs/src/sys/net/if_vxlan.c,v
diff -u -p -r1.100 if_vxlan.c
--- if_vxlan.c	31 Oct 2024 11:41:31 -0000	1.100
+++ if_vxlan.c	15 Jun 2025 13:45:51 -0000
@@ -944,7 +944,6 @@ vxlan_tep_add_addr(struct vxlan_softc *s
 	if (error != 0)
 		goto close;
 
-	m_inithdr(&m);
 	switch (vt->vt_af) {
 	case AF_INET:
 		sin = mtod(&m, struct sockaddr_in *);