The issues are to do with the dot projector in the iPhone X, which flashes 30,000 infrared dots onto the user’s face in order to check that it really is the user’s face—if so, they get to log in. The production of the module has to be extraordinarily precise and, according to a Wednesday Bloomberg report, this is where the problem lies.

Per Bloomberg’s unnamed sources, Apple’s manufacturing partners—LG Innotek and Sharp—were at one point having to discard four-fifths of the dot projectors they made, as they were unusable. The report states that they slowed down production as a result, and to speed it up again ahead of the iPhone X’s November 3 launch, Apple “relaxed some of the specifications for Face ID.”

However, Apple strongly disputes this. “The quality and accuracy of Face ID haven’t changed. It continues to be one in a million probability of a random person unlocking your iPhone with Face ID,” a spokesperson told Fortune. “Bloomberg’s claim that Apple has reduced the accuracy spec for Face ID is completely false and we expect Face ID to be the new gold standard for facial authentication.”

Bloomberg also noted that Apple lost one laser supplier, Finisar, early on in the process, due to Finisar not meeting Apple’s specifications. It also said Apple is struggling to find suppliers beyond Samsung to deliver OLED screens for the phone.

Meanwhile, Apple CEO Tim Cook addressed the rumors of iPhone X production problems in a Buzzfeed interview published on Tuesday. “We’ll see what happens, but we’ll be working as hard as possible to make as many as possible,” he said.

https://www.youtube.com/watch?v=Rb3URd5Y5X0&w=560&h=315

This article was updated to include Apple’s comment, which came in later on Wednesday.