Absolute bullshit, especially for a city bike.
Stress cycle is an issue but city bikes are over engineered and don't see a lot of stress compared to every other type of bikes.
I've used alu bikes over 30 years old daily and I had no issues whatsoever, that's how I went to school everyday for 3 years, and that was a race bike that actually had been use for racing in the past
Online posts make it sound like alu bikes self destruct at 5 years and a day...