Why I cannot open my YouTube subscription in my new phone?

Hello there Ramoskike,

Welcome to Apple Support Communities. The steps to resolve this issue with your YouTube app can be found in this Apple Support article: If an app on your iPhone or iPad stops responding, closes unexpectedly, or won’t open - Apple Support

"Close and reopen the app

Force the app to close. Then open the app to see if it works as expected.

Restart your device

Restart your iPhone or restart your iPad. Then open the app to see if it works as expected.

Check for updates

To see if updates are available for the app, open the App Store, tap your profile icon, then scroll down to see if updates are available. If updates aren't available for the app, update the software on your iPhone or iPad.

Delete the app, then redownload it

Delete the app. When you do this, you might lose data that was stored in the app. Then redownload the app. Then check to see if the problem with the app is fixed."

Feel free to reach back out if you have any questions.

We hope this helps you.