@dlakelan @dlakelan @eduperez , Thanks guys !

@dlakelan, just to answer your question, my hosts on the LAN can ping ULA addresses.

The issue is with 2XXX public IPv6 addresses,

I am trying to test hop by hop, where is it losing

OUT PACKET,

My LAN HOST => My OpenWRT(Relay Mode) => My ISP Router => Destination

IN PACKET

Source => My ISP Router => My OpenWRT(Relay Mode) => My LAN HOST

The routes are correctly advertised on my LAN host