If you often visiting cafe to hanging around with your friends, you should be careful using public WiFi. We don't know how the cafe set the security for their customers but I heard the cafe can trace their customers activity while connecting to the WiFi.
If you're worried about being tracked via Wi-Fi, use your mobile data. I think everyone with a smartphone now has a mobile data plan (with a high data limit).
By the way, your mobile operator will still be monitoring your activity.

I know this from conversation with my cousin when I meet him few days ago, he told me that many cafe's offers free WiFi to attract customers visiting their place. But some local cafe or public service places use this chance to gets the internet history of their customers, even they can get the log of banking credentials of their customers.
How does your cousin obtain this information? Is he technically knowledgeable (a technical specialist) or was he involved in the processes he describes? Or is this just hearsay?
If you use free WiFi from a cafe or local store or hotel, you should not login to your mobile banking app but if you really need to login to your mobile banking app, make sure you use data connection from your phone to avoids the hacking.
If you have mobile internet on your phone, why use free Wi-Fi? Out of greed?
Your security will be your responsibility so make sure that you can be careful if you connect to public WiFi and don't login to anything personal.
Perhaps it would be better to have 2 smartphones? Many people have older devices that could be used for online banking, crypto wallets, and other sensitive information. In reality, security isn't the cheapest option, and having "everything valuable" on one device creates additional risks (theft, loss, hacking, data leakage).