VPN Site to Site

I build site to site vpn connection from fortigate in HQ and sophos xg in branch.

In the tunnel interface in fortigate listen on port8 with ip address xx.xx.xx.230

The vpn connection is established, the branch and hq can communicate but if i traceroute from branch to hq i feel strange why the traffic passing thru another ip in fortigate xx.xx.xx.246 and not to xx.xx.xx.230?

Here my tracert result

Tracing route to 10.7.208.52 over a maximum of 30 hops

1 <1 ms <1 ms <1 ms 10.108.150.1
2 22 ms 16 ms 20 ms xx.xx.xx.246
3 29 ms 20 ms 20 ms 10.7.101.2
4 21 ms 23 ms 18 ms 10.7.208.52