Data source in PowerQuery | different amount of rows

In the first picutre you see all the sheets my Excel workbooks have (I have around 50 in one Folder). When I open the "PowerQuery" sheet some of them are opened with 8 rows and some of them with 5 (like you see in picture 2 and 3). In the last picture you see the data source. 

Does somebody know why sometimes the sheets "PowerQuery" has sometimes 8 and sometimes 5 rows in PowerQuery?