Hi
I encounter same kind of problem with 6.12.69+deb13 in Trixie.
My working configuration with 6.12.63 is broken after upgrade to 6.12.69.
Unlike your bug on bookworm, in my configuration packets are sent but
silently dropped on remote side.
I found something on kernel 6.12.67: some changes was made on ip6_tunnel
and other modules. Here is a commit example for 6.12.67:
df5ffde9669314500809bc498ae73d6d3d9519ac, there is also other commits on
macvlan and ip_gre
I cannot be sure those changes introduce the bug, I am not a developer.
I found also https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1127597
You should have a look on 6.1.x for same kind of bug fixes.
Hope it helps!
F!nTcH
