• I created a new calligraphic brush: roundness 68%, angle 16, size 28, pressure dynamics 10%.
• I drew a bunch of lines with it
• exited the file
• opened it again on iPad, selected one of the lines with the selection tool and boom - it reverted to a rounded brush stroke
• happens also if I open the file in desktop
• screenshots attached

I've tried this numerous times with all new files and it's consistent. Posted this on the Adobe Community and I shared my file with an Adobe Community Professional and she experienced the same thing with it.