Always has been. Julie of the Wolves is a Newbery winner and the sexual assault in the first quarter of the book is central to the entire story. The Giver is another, and deals with euthanasia and infanticide (literally 'abortion after birth'). Number the Stars, again a Newbery winner, dealing with escaping genocide. The Slave Dancer - guess that topic? Summer of the Swans, with a mentally disabled sibling? Shiloh - animal abuse. Maniac Magee - racism.
And they've always been being banned for these things. And these are just from the <100 Newbery winners.
Let's be real. They're probably fine with Maniac Magee not being banned.
Thats the only book I've read out of the ones that you shared. Interestingly, that was the book my 3rd grade teacher decided to read aloud during storytime. When I read it again as a teenager I was questioning the choice, but even at age 8 I thought it was well-written.
And they've always been being banned for these things. And these are just from the <100 Newbery winners.