For 32 years, Greg Tutunjian, 73, has picked up his coffee at Starbucks. He’s partial to its dark-roast Red Eye, but starting to question his loyalty to the chain that serves it up.

While waiting for his order, Mr. Tutunjian watches impatiently as baristas whip up Iced Brown Sugar Oatmilk Shaken Espressos or other foamy, iced, caramel-topped drinks for drive-through or mobile-app orders. Minutes tick by before he is finally handed his coffee (dark-roast coffee with a shot of espresso).

Even more annoying for Mr. Tutunjian is when Starbucks’s mobile app tells him that a bag of his favorite coffee beans — Komodo Dragon — is in stock when it isn’t.

“I will go to four or five Starbucks in my local area and have the same experience. I check the app right before I go inside and it says it’s there, but when I arrive, the people working there say, ‘Oh, we don’t use or look at the app,’” said Mr. Tutunjian, a software consultant from Newton, Mass. “I walk out empty-handed.”

Mr. Tutunjian’s frustrations are now Brian Niccol’s problems.

Mr. Niccol took over as the Starbucks chief executive on Sept. 9 and quickly laid out what’s wrong at the company. During his first week on the job, he panned the Starbucks store experience in a letter posted on the company’s website: “It can feel transactional, menus can feel overwhelming, product is inconsistent, the wait too long or the handoff too hectic.”

The numbers bear him out. Last week, the coffee giant issued a preliminary report that showed a 7 percent drop in global same-store sales for the fourth quarter amid “a pronounced traffic decline” in North America — 10 percent lower than it was a year earlier. The company, in a sign that it will take time for Mr. Niccol to fix Starbucks’s issues, suspended its financial guidance for the 2025 fiscal year.