To start working with the Budget module in Expenses, you need to activate them. Consider How to Set Up the Expenses module to go through the process step-by-step.
With the activated function, you
The Budget will be completely removed from the document, which was taken for Revision.
Thus, if you deactivate the Budget function, it will still be displayed in the documents with Paid and Approved statuses. However, it will become unavailable in Pending and Draft Expenses and get removed entirely if the document is taken on Revision.