When Next.js app router opt out static rendering

[DevDynasty0]

I have a little confusion about when Next.js app router opt out static rendering.

• Next.js switching to dynamic rendering explanation says, “During rendering, if a Dynamic API or uncached data request is discovered, Next.js will switch to dynamically rendering the whole route.” Link
• However, in Next.js 15, the response from fetch is not cached by default. But even if we use fetch in a route, and do not use any Dynamic APIs anywhere else in this route this route is still statically prerendered at build time. Link

My question is if a route with an uncached fetch request is statically prerendered then what does it mean by “uncached data request” in the Next.js switching to dynamic rendering explanation?