I installed flipkart from apk. And without logging in searched for mobile phones.Then cleared app data and started VPN and then opened the app again but I was getting recommendations of searched phones. How flipkart bypassed VPN? How can we sure that browsers don't really bypass VPN?
It didn't bypass the VPN. The apps use your other identifications such as "Advertising ID" identify you. Then this information is used to give you suggestions/recommendations based on your previous browsing or search history.
Most apps will also keep a local cache. So, unless you have cleared data for the app, the app knows everything you previously did.