ALV Error: Overwritten protected field__layout

Recently, when doing ALV development, I stumbled across this problem:

The data is output normally, but when I go back or double click the line, the error tip is:

Error at Assignment:overwritten protected field.

From the wrong hints, the program tries to overwrite the protected field during execution.

After repeated examination, it was found that the box_fieldname was set in layout. The field that corresponds to the set value is not in the table.

It would be nice to comment out the statement later.