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OCBC Bank locks out mobile app if 3rd party apps are detected
(www.zdnet.com)
This is a most excellent place for technology news and articles.
Yeah, it's the same for iOS when you sideload any app. You can always get an SMS OTP to login though
For sideloaded apps I can understand the rationale at least, but a stock phone really shouldn't have any issues with a genuinely downloaded app from google play.