Food Wars! / Shokugeki no Soma - Pack It Up Boys, Shokugeki no Soma is Over, The Illustrator is Obviously Tired, Otherwise, There's No Way He'd Make the Amateur Mistake of FUSING A MAN'S HEAD TO JAIL BARS

I've seen the same in other manga, when the artist wants to show people behind bars but wants their faces to be fully visible so they make the bars selectively transparent like this. Although in this case it's worse because the bars are so far apart that just by moving the characters around a bit their faces would have been fully visible anyway.