Just answering my own question in case someone needs this info:
According to this document listing acf code –
https://docs.wpdebuglog.com/plugin/advanced-custom-fields/5.8.8/function/acf_verify_nonce/
acf resets the nonce to “false” upon verification. So “false” as value for ‘acf_nonce’ in the $_POST actually means ‘verified’.
