Charging speed slower than expected

Hi, I recently got the Anker Prime Power Bank 27650. Currently I am using a Lenovo Thinkpad X1 Xtreme Gen3 which has * Rapid Charge technology available with 65W or above PSU. However, when using the cable given with the portable charger which labels ‘140W’ max as well as other cables capable of 5A. The max seems to be capped for some reason. Anyone knows the reason why? Do I need to get 240W cables?