Apple has designated the iPhone 6, released in back 2014, as a "vintage" product.
Apple considers a product vintage when it has stopped selling them "more than 5 and less than 7 years ago". Apple considers a product obsolete when it has stopped distributing them for sale more than seven years ago, and has just added the iPhone 6 to its list of vintage products.
Apple unveiled the iPhone 6 and 6 Plus on September 14, 2014. They had 4.7-inch and 5.5-inch displays, respectively. They shipped with iOS 8 and were equipped with Apple's A8 chip and M8 co-processor. They were lighter, thiner and had notably larger displays than the iPhone 5 with much higher resolution, too. Along with iOS 8, Apple up-ended payments with Apple Pay, thanks to the new NFC chip in the models.
Via 9to5Mac, Apple had already designated the iPhone 6 Plus a vintage product even though it was released alongside the iPhone 6. That's because Apple continued to sell the iPhone 6 in some regions after discontinuing the Plus model. The last version of iOS that can run on an iPhone 6 is iOS 12 from 2018.
The iPhone 6 was also part of Apple's subsequent battery fiasco. In iOS 10.2.1, released in 2016, Apple introduced changes to stop them unexpectedly shutting down and manage battery ageing and faced accusations that it intentionally slowed its devices down over time. Until 2018, Apple still reported quarterly unit sales of iPhones. In Q1 2015, the first full quarter since releasing iPhone 6, it reported a record profit on the back of 74 million iPhones sold, up from 51 million from Q1 2014.