Man pages matching name curlinfo_appconnect_time_t in section 3:

CURLINFO_APPCONNECT_TIME_T.3.en	debian 10 / libcurl4-doc
CURLINFO_APPCONNECT_TIME_T.3.en	debian 11 / libcurl4-doc
CURLINFO_APPCONNECT_TIME_T.3.en	debian 12 / libcurl4-doc