Python uses openpyxl to read the date in Excel cells, and many decimals appear after seconds.

python Use openpyxl read excel Date in cell , Many decimals appear after seconds .
Contents in cells ：2022-7-1 17:50
Use the following statement to read ：
ws.cell(row=2, column=30).value

The result is ：
2022-07-05 17:49:59.995000

Why is this ？