Apple didn't pull in the most impressive numbers with the iPhone during the last quarter, and its suppliers are starting to get worried about what's ahead.

The earnings report for FY18 Q4 wasn't a disaster by any stretch, but Apple couldn't hide the fact that hardware sales had shrunk. Now it's unclear if there will be a turnaround during the holidays as multiple suppliers downgrade estimates. Across the supply chain, the Cupertino-based company appears to be losing confidence from its partners.

With the iPhone struggling to maintain strong demand, another supplier decided this weak to lower its revenue forecast. AMS, which contributes to Apple's Face ID technology, has decreased its estimate by nearly $100 million. The supplier thinks it'll earn around $480-$520 million.

Other suppliers who are skeptical about the iPhone's turnaround include Qorvo, Lumentum, and Japan Display. All of them also reduced their estimates this week.

Still, the entire company continues doing well. Apple was able to profit more than $14 billion last quarter. It's just concerning that, as hardware sales fall, Apple started hiding unit sales. There was an appreciation for transparency, but Apple's needs to spur growth and woo investors again.