It looks like DUS is losing F service on the EWR and ORD services starting 19FEB. Expertflyer only shows
J9 C9 D9 Z9 Y9 B9 M9 U9 H9 Q9 V9 W9 S9 T9 L9 K9
and rows 1 and 2 are displayed as part of C, with the seats being blocked. Trying to display an F seat map results in an error.