Cant use Datetime block to format the datetime in Evaluate of Flows?

[mission-participant9 (Hua Tao)]

Just as the title.
1 It works when I input in the Evaluate.
2 It doesn’t work when I run the flow. A timestamp value is automatically converted to a string or number if required. https://learning.postman.com/docs/postman-flows/reference/data-types/