MongoDB Charts now allows users to add new fields in the chart builder and change the types of existing fields, making it easier to visualize data that has a highly variable schema. This update addresses challenges such as missed fields, calculated fields, and type conversions, enabling users to create more accurate and informative charts. The new features are available as part of MongoDB Atlas, and can be accessed through the chart builder by clicking on the "Add Field" link and selecting the desired option. With these updates, users can now manipulate fields in three ways: adding missed fields, adding calculated fields, and changing the type of existing fields. This makes it easier to build charts that accurately represent complex data structures.