Task Custom Fields is always on and cannot be disabled.
Read the full Custom Fields documentation
Learn how to create, configure, and restrict custom fields for your workspace.
Arca Apps
Task Custom Fields
Add your own fields to tasks to track any data your workflow needs. From ratings and budgets to people and dates.
Task Custom Fields lets you define workspace-level fields that appear on every task. You can create fields for numbers, dates, dropdown menus, checkboxes, text, ratings, money amounts, and people assignments. Each field can be restricted so only specific members can see it.