https://www.zabbix.com/documentation/6.0/en/manual/installation/requirements#required-software
says:

Libcurl version requirements:
- SMTP authentication: version 7.20.0 or higher
- Elasticsearch: version 7.28.0 or higher

In 6.0.24, probably in ZBX-23490 we have started to use function "curl_easy_header"
https://curl.se/libcurl/c/curl_easy_header.html which have been added in much more later libcurl releases, as stated from 7.83.0

Not sure how, but on my testbox Ubuntu 22.04 with "7.81.0-1ubuntu1.15" I could compile zabbix 6.0.25 successfully.

Probably this should be addressed.