Deutsche Bank said Tuesday it's that bullish about the Apple iPhone 8.

It's a stark contrast to many other banks that have suggested Apple is about to sell record numbers of iPhones in an upcoming "supercycle" of upgrades.

Firms such as Credit Suisse, Citi and Instinet have all referred to the so-called supercycle that will drive a new Apple rally, though Deutsche Bank thinks Apple's facing just a regular upgrade cycle.

"The real supercycle was the iPhone 6 and iPhone 6 Plus cycle," Deutsche Bank said. "That cycle saw peak iPhone shipments of 231M in FY-15."

The bank estimates Apple will ship about 230 million units in fiscal 2018, far below Wall Street's consensus of 244 million units.

The firm said Wall Street's expectations are "too high" and that "investors will be disappointed by iPhone growth" in fiscal 2018 and 2019. This is despite expectations that Apple will launch a brand new high-end iPhone 8 with wireless charging, a new brighter and colorful OLED screen and a display that takes up almost the entire front of the phone.

"The market has become overly optimistic on iPhone's potential sales into the upcoming iPhone launch this fall, and is ignoring the fundamental challenges Apple faces in the smartphone market, which include saturation in mature markets, elongating refresh cycles, declining share plus increased competition in China, and a growing secondary market," Deutsche Bank said. It added that it is struggling to understand where the new iPhone buyers are coming from.