https://docs.haproxy.org/3.4/configuration.html#3.2-tune.bufsize
Documentation should state hard upper limit for tune.bufsize:Sep 03 13:36:40 vrrp1 hapee-lb[2539175]: [ALERT] (2539175) : config : global.tune.bufsize must be below 256 MB when HTTP is in use (current value = 268435456).
