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When I download sheets to xls, I get an error when trying to open with MS Office 2024 (stand alone) and all formatting is lost: column widths, bold, etc. are all gone.
It is time-consuming to re-do the formatting in xls - which is the format I need to send the file to others.
I use Proton Sheet because it is a better cloud alternative but losing formatting when downloading is a HUGE problem.
If developing a download to an open source file type (ods) is technically easier than fixing the xls download, please do that.
As it is, xls results in a very similar file when I open in Excel as if I had downloaded a csv.