I often hear UX folks designing mobile applications for one handed operation of the device. But I have seen many people using two hands to use a phone quite often, perhaps because the screens of many phone models have become larger and even low cost phones now have large screens.
Have you come across any authentic research or data showing any recent trends?
There's certainly going to be a lot of data collected by Google and Apple on one-handed usage, and probably by many device makers. But that data is valuable for creating private value to those companies. I can't see why they'd be interested in sharing (much of) it with anyone when they can use it to their own advantage in design. Anecdotal information isn't practically useful, such as your observations. I would however agree with you that unless there's a physical limitation, people have a preference for two-handed device operation, even when one-handed operation is available.