I'm not sure if this is a Big Sur issue or an Apple Silicon issue or a LibreOffice issue but the fonts are fuzzy (I migrated from my 2015 MacBook Pro running Mojave to an M1 mini running Big Sur). I haven't figured out how to fix it so I'm going to switch to Numbers. The fonts are fine on Numbers. I was using LibreOffice as I like to go back and forth between Windows and macOS with my spreadsheets. I will just use LibreOffice on Windows and Numbers on macOS. I don't see the fuzzy fonts issue on LibreOffice on Windows.
I did play around with different fonts and those that are widely used.
I did play around with different fonts and those that are widely used.