It appears the new HAProxy template isn't properly parsing some values from the stats page. I've purposefully generated some 404 errors on a server being monitored and saw those errors appear in the stats page in the section of the HAProxy frontend called "https" (see screenshot haproxy_stats_page_screenshot.png).

Zabbix reports the number of 4xx errors as 0 (see screenshot zabbix_last_500_values_screenshot.png).

I've attached the source html file and csv file that Zabbix retrieves from the HAProxy stats interface (after having replaced sensitive customer and server names), as well as the json file that Zabbix has made of this data. This json file appears to be transformed correctly and contains the proper value of 4xx errors for the "https" frontend, as you can see on line 138:
"hrsp_4xx": "84",
 
This leads me to believe the issue resides in the jsonpath preprocessing of item prototype haproxy.frontend.hrsp_4xx.rate.

It's possible that other items are also being incorrectly parsed, but this item tracking 4xx errors is the only one so far that I've been able to prove wrong.

Both my server and agent are running Zabbix 4.4.4.