Motorola released the Moto G4 Plus back in 2016 and promised it would receive two major updates. A while later, the company went back on its word and claimed the mid-range phone would not get the update, prompting a media outcry which forced it to once again promise to deliver Oreo. It's been 16 months since then, though, and the G4 Plus is still on Nougat.
https://www.notebookcheck.net/Over-a-year-after-promising-Oreo-for-the-Moto-G4-Plus-Motorola-is-yet-to-do-so.400891.0.html