ip6gre tunnels fail to be decapsulated in v6.12.67 so never appears on the GRE interface.
Reverting the following commit fixes it: commit df5ffde9669314500809bc498ae73d6d3d9519ac Author: Eric Dumazet <[email protected]> Date: Wed Jan 7 16:31:09 2026 +0000 ip6_tunnel: use skb_vlan_inet_prepare() in __ip6_tnl_rcv() [ Upstream commit 81c734dae203757fb3c9eee6f9896386940776bd ] v6.19 works but I've not been able to identify a subsequent commit that should also be backported to the stable tree.
