The Samsung Galaxy Z Fold3 is the first foldable to support the S Pen (or any advanced stylus, really). But it lacks backwards compatibility – you can use only one of two styluses, the S Pen Fold Edition and the S Pen Pro (the latter needs to be switched into foldable mode). We already established you can't use a different S Pen, but what if you try it the other way around? As it turns out using the S Pen Fold Edition on a non-foldable phone, say the Galaxy S21 Ultra, doesn’t work either. The phone detects it, but it doesn’t function properly – for some reason the stylus always works in...
Source: https://www.gsmarena.com/the_s_pen_fold_edition_doesnt_work_on_nonfolding_galaxys_the_z_fold3_cant_use_older_s_pens-news-50547.php
