I have tried rc5 in x86_64 virtual box for testing it with docker such as in the tutorial Running PiHole on OpenWrt (x86/RPi) using Docker - Tutorial/Experiences. The problem persists from rc4, containers are not able to access the WAN. Even a basic run of a container such as docker run -it nicolaka/netshoot ping 8.8.8.8 (from here) to try access the WAN interface on openwrt fails with same error as before.
root@OpenWrt:~# docker run -it nicolaka/netshoot ping 8.8.8.8
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
From 172.17.0.1 icmp_seq=1 Destination Port Unreachable
From 172.17.0.1 icmp_seq=2 Destination Port Unreachable
From 172.17.0.1 icmp_seq=3 Destination Port Unreachable
^C
--- 8.8.8.8 ping statistics ---
3 packets transmitted, 0 received, +3 errors, 100% packet loss, time 2081ms
On 21.02, the containers are able to access the internet, similarly on normal linux distributions such as Ubuntu 22.04. So far docker networking seems broken with the new 22.03 rc's.