I shot a series of portraits and for a few I accidentally activated sports mode.
Not sure how, either it was a bug or possibly the touch screen...
Anyway the created files (Raw M) are magenta when opened in Capture One
and even in Black and White fully zoomed in there are very fine horizontal lines
Capture One 11.3 Fuji XT3 and RawM files (via SportsMode)
It is likely to be the same if medium Raws are selected directly (not forced by the Sports mode)