The site says this information comes from a source who works on the Maps app for Apple.
iOS 16 will not be available for download on A9 chips, namely: iPhone 6s, iPhone 6s Plus, iPhone SE 2016. The minimum union should be the A10 chip, which guarantees decent performance for streaming, video games and the interface in general. This is the one we had on the Apple TV 4K 2017 for example.
Additionally, iPadOS is said to drop support for iPad Mini 4, iPad Air 2, iPad 5, iPad Pro 9.7 and 12.9 inches (2015).
We'll let you know if any evidence surfaces to corroborate these claims. Apple will likely unveil iOS 16 in June 2022. Please download the iClarified app or follow iClarified on Twitter, Facebook, YouTube, and RSS for updates.