2.5.1 upgrade to 2.5.2 breaks HAProxy

cukal

Upgrade from 2.5.1 to 2.5.2 breaks HAProxy "apply" action in my case.
The first save action is already way longer than usual, but at least it finishes.
The apply on the other hand takes a very long time, and eventually times out:

Jul  8 00:44:04 pfSense2 nginx: 2021/07/08 00:44:04 [error] 921#100204: *28 upstream timed out (60: Operation timed out) while reading response header from upstream, client: 172.24.254.53, server: , request: "POST /haproxy/haproxy_pools.php HTTP/2.0", upstream: "fastcgi://unix:/var/run/php-fpm.socket", host: "172.25.1.1:8443", referrer: "https://172.25.1.1:8443/haproxy/haproxy_pools.php"

Nothing special, some ssl-offloading shared frontends, some backends with client certs.

Reverting the VM snapshot and returning to 2.5.1 makes haproxy functional again.

Gr,
Cukal