Printing with incorrect proportions

Hello everyone,

I've been trying to solve a formatting issue in Excel for a little while now.
I searched Google to see if others had the same problem as me, but apparently not (which doesn't reassure me). Therefore, I'm turning to you.

Here's my issue:
When I print my Excel sheet, the proportions are not maintained. For example, if I insert a shape that is 15 cm wide and 15 cm high (to have a perfect square or circle), once printed, it is slightly flattened.
I've tried different page layout settings, but nothing works. I must be missing something.

Currently, my page layout options are as follows:
-Orientation: portrait
-Scale to fit: 100% normal size
-Paper size: A4
-Print quality: 300 dpi
-All margins are set to 0 cm
-No header or footer
-No print area

Once printed, the circle measures 16 cm wide and 14.5 cm high... and unfortunately, it's flat enough to be noticeable. In fact, I can already see it in the print preview.
I tried saving the workbook as a PDF to see if it was an issue with the printer, and it’s the same problem. On screen, the circle is distorted whereas it isn’t in Excel (measured on screen too ^^).

You may wonder why I'm trying to use Excel to print a circle...
Actually, I'm creating a ready-to-use Excel file for a friend who doesn't know this spreadsheet tool very well. Based on certain information, the document calculates different data and produces a page ready for printing. At the top of this page, there's the logo of his small business (a circular logo). That's when I noticed that his logo was distorted when printing.

That's all, I hope I've provided you with all the necessary information.

Thanks in advance for your responses,
Have a good evening.