https://www.theverge.com/2018/11/22/18107795/iphone-x-production-resumed-weak-demand-2018-models-rumor

Apple has resumed production of the iPhone X due to weaker than expected demand for its latest XS and XS Max models, according to a report by The Wall Street Journal. The move is allegedly due to an agreement made with Samsung to purchase a certain quantity of OLED screens. With this year’s OLED-equipped models failing to sell in the quantities needed to fulfill the terms of the deal, the report suggests that Apple is turning to last year’s model for a solution. Apple ceased selling the iPhone X in stores when the XS was first released.

The iPhone X is thought to be cheaper to produce than the XS or XS Max thanks to its age, which means components and manufacturing equipment is cheaper, according to the WSJ report. In the past, legacy models have been produced when there’s enough demand for them in certain markets.