The Foundation sees this as a contradiction to the EU’s own interoperability goals. Although XLSX is standardized as OOXML according to ISO/IEC 29500, Microsoft’s implementations often deviate from the specifications. Furthermore, features often change undocumented, which complicates compatibility with open-source software such as LibreOffice.
That is supposed to be even with Microsoft office, because it changes the fonts without warning and adjusts the margins according to the default printer. It’s not a format designed to be shared with other people