XHR timeout on cold start

There is RPI 4 Model B with OpenWRT built by myself.
HEAD detached at v21.02.5.

On cold start, there is an XHR /ubus/ call that fails one first time after 20 seconds timeout due to luci-app-ddns. On the very first time after reboot, it delays ubus underhood calls on the overview page. It does not concern any other pages, although it the page which is welcome user by default.

This leads to a half-loaded LuCI start page and a huge (21 sec) interface delay, which is more than 20 hardcoded delay.

The solution for me it to exclude that luci-app-ddns package from my .config.