Man pages matching name sasl_server_userdb_checkpass_t in section 3:

sasl_server_userdb_checkpass_t.3.en	debian 10 / libsasl2-dev
sasl_server_userdb_checkpass_t.3.en	debian 11 / libsasl2-dev
sasl_server_userdb_checkpass_t.3.en	debian 12 / libsasl2-dev