It’s a new option on the Excel.Workbook function called InferSheetDimensions. Here’s what the docs for the Excel.Workbook function say:
Can be null or a logical (true/false) value indicating whether the area of a worksheet that contains data should be inferred by reading the worksheet itself, rather than by reading the dimensions metadata from the file. This can be useful in cases where the dimensions metadata is incorrect. Note that this option is only supported for Open XML Excel files, not for legacy Excel files. Default: false.
Read on to understand when that might happen.