shadcn styles (which are correct at the beginning) suddenly went wrong without any warning [next-15, react-19, tailwind-4]

[Coloneliu]

Hi:
I have met something very confusing with shadcn.
When I started a nextjs project and installed the shadcn successfully by

1. $ npx create-next-app@latest --use-pnpm
2. $ pnpm dlx shadcn@latest init
3. $ pnpm dlx shadcn@latest add button

The Button was displayed correctly at the beginning when $ pnpm dev

But when I restarted the server by $ pnpm dev, the shadcn Button went wrong.

I have tried several new projects, but the same error happened in each time.

Here is the project and root page.tsx, I didn't modify any config files:

Here is the root page's appearance with wrong Button styles(which should have black backgound color, not the same with origin button):

---

The Button should be like:

Thanks for viewing and wish some answers.
Best wishes!

[Coloneliu]

I have temporarily found a weird way to fix it.

Never add the components/ui to .gitignore

I have test this many times, once I add the components/ui to .gitignore and pnpm dev, the Button's styles went wrong;
If I remove this and pnpm dev, the Button style become correct.

But, I have no idea why this happeded