I think I know what was going on here. I can't find a source (too many false hits on tech news sites), but a batch of counterfeit displays for one model of iPho

I think I know what was going on here. I can't find a source (too many false hits on tech news sites), but a batch of counterfeit displays for one model of iPhone used a touchscreen controller from a much older model. When a new version of iOS was released which no longer supported that older model, Apple removed the drivers for its touchscreen controller from the OS, under the assumption that they were no longer necessary. This had the unexpected effect of making those displays stop working. This wasn't intentional -- it was an inadvertent result of routine code cleanup -- and Apple added the driver back in a later OS update to restore functionality, and added messaging to indicate to users if their display wasn't a genuine Apple part.