Currently, the text field has a limit of 255 characters, even when not using the next-gen.
We had a feature request suggesting to manually increase/decrease the limit, but it was closed as "Won't do":
As a workaround, you can use a free text field.
Sorry for the misunderstanding, indeed the fields created in the next-gen project are independent and the workaround provided on that feature will not be applied to the new projects.
I've created a new feature request based on your question:
Please, click on vote and watch to receive updates.
Hello friends! From the community that brought you Welcome Wednesday, Throwback Thursday and Friday Fun, welcome to Taco Tuesday, a weekly discussion about all things Trello. The best part? One Tac...
Connect with like-minded Atlassian users at free events near you!Find an event
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no Community Events near you at the moment.Host an event
You're one step closer to meeting fellow Atlassian users at your local event. Learn more about Community Events