People who can't speak Cantonese in Hong Kong will have a great influence on communication first, because Hong Kong people really can't speak Mandarin. Hong Kong sounds funny and it's hard to fully understand. What floor we usually talk about is gay to them ~ instead of racking their brains, it is better to communicate in English. Moreover, people who can't speak Cantonese will expose their status as "Yankee" as soon as they speak. Most people who can't speak Cantonese in Guangdong are foreigners. We all call them "Americans", which is more or less a contempt for people. As strangers, Hong Kong people will definitely feel more intimate and identify with Cantonese speakers.
Besides communication, it is also influential for friends who can't speak Cantonese to find jobs in Hong Kong. I have noticed that many recruitment units in Guangdong require barrier-free communication between Cantonese and Mandarin, or give priority to those who can speak Cantonese. Hong Kong is no exception. After all, most people in Hong Kong mainly speak Cantonese, so it is more advantageous for the company to recruit an employee who can speak Cantonese. Of course, it doesn't matter if you can't speak Cantonese. Don't be discouraged. Although many Hong Kong friends are really poor in Mandarin, it is no problem to understand. Maybe you should pay more attention to their Hong Kong dialect and Cantonese.