Deal Size Not Mapping to Opportunity Revenue During Lead Conversion

When a Lead is converted to an Opportunity, we have enabled the copy maps to transfer the Deal Size value to the Opportunity Revenue (standard field) based on the client’s requirement. However, even after configuring the copy maps, the Deal Size value is not flowing into the Opportunity Revenue field.
We need to know if it is possible to achieve this functionality, and if so, what approach can be used.

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