До какой последней версии Next.js вы обновились на проекте?

I cannot specify a particular version of Next.js that was upgraded in your project, as it depends on the timing and update policies of your team.

However, to find out the latest version of Next.js, you can check the official repository on GitHub or npm:

npm show next version

For updating the project, the stable latest version is usually chosen, considering compatibility with used libraries and project requirements.

If you need to answer in an interview, it is better to honestly state that you upgraded to version X.Y.Z (indicate the current version at the time) and describe your migration experience and how you solved potential issues during the update.