Instagram shortcode for user post comments information
you should use

The end_cursor will come after the first returned response. For the next page, you need to send it, the incoming data should be sent again as json.

For example:
shortcode: CeeEML9lELj

Bad shortcode request:
https://www.instagram.com/p/CeeEML9lELj/
Correct shortcode request:
CeeEML9lELj

Bad end_cursor request:
“QVFDSlNIOEozWWZTbElnWnNHRzJsSmNvalJUUy1zNV9XUWVxZ0FjU1Q0YWVmbVhCWWN1WkhYS0hZSW4xamtHcmpMTnBNQlVVZUV5MUlSRjNsUnF4Y3FzNzhmVGdaNUVwWWRkanV4UG9odkJGMVE=”

The correct end_cursor request can also come in different keys, it will always be json.
{“server_cursor”: “QVFDSlNIOEozWWZTbElnWnNHRzJsSmNvalJUUy1zNV9XUWVxZ0FjU1Q0YWVmbVhCWWN1WkhYS0hZSW4xamtHcmpMTnBNQlVVZUV5MUlSRjNsUnF4Y3FzNzhmVGdaNUVwWWRkanV4UG9odkJGMVE=”, “is_server_cursor_inverse”: true}

Another incoming json value:
{“cached_comments_cursor”: “17951132692995101”, “bifilter_token”: “KFEBEACoACgAGAAQAAgACAAIAAgA_n__7___n19f___9u97133__-3L9_nUdpm6h95k3eiE73__3v9cf__7_3-v-zuf____b7_9eYfT3oDCNQgQA”}