Form validation doesn't work on Next.js 15 until first submit

[mfazekas]

I've tried to use form in https://ui.shadcn.com/docs/components/form#installation. Followed the steps as is - see the form component here. Works great with next.js 14, but for 15, it doesn't show validation errors until I press submit.
I don't have react compiler enabled.

App is deployed to:
https://next-15-form-chi.vercel.app

Code is:
https://github.com/mfazekas/next-15-form

To reproduce type 'a' note that no validation error is shown

Press submit
Note that validation error shown and it's correctly changes as I add/remove characters

[mfazekas]

Actually the issue here is with missing mode: 'all'