There is a "discussion" going on about Progressive Web Apps and the user experience currently provided by Flipkart.
If they are not sure the site is not fully working on a browser X, they block it through user agent sniffing. It is a double fail strategy.
- User Agent sniffing is often a fail strategy. It can be bypassed through user agent override, which as browser vendors we often do to provide users the access they deserve. It's a silly game if you think about it. The Web site blocks the browser. The browser vendor does UA override for this site. The site doesn't record statistics of customers with this browser. So no understanding if they really have, even if tiny, a market share there.
- Blocking users is just bad for your brand. It means "Hey you, we don't accept your choices. You are not welcome in our place". It's violent. It's a lack of respect.
A path in between? Managing user expectations.
Create your Web site in a way which gives universal access, what is called progressive Web. It works in the simplest environment and offers a better experience for users with different type of choices.
But if you really have to prioritize your work, then just say it, inform the user once, that this site has been fully checked on these platforms X, Y and Z and it might fail in some areas. That you welcome bug reports explaining in which ways it fails and that you are interested by receiving some hints on how to fix it. This is thousand times better than blocking a user.