Quiet censorship from within Denver Public Library?

I just bought a used book from a local Denver bookseller via Amazon. It arrived fully labeled for the Denver Public Library system and had been officially stamped as decommissioned.

It's an LGBT book. The cover has a big rainbow, so it's obvious at a glance.

I am aware that librarians routinely weed items for a variety of valid reasons. But this book was in good physical condition, was the only copy available, and is not outdated.

The Denver Public Library is vocal against book banning, which makes this upsetting. I admittedly do not have all the facts, and I have no intention of fear-mongering. But this seems too on-the-nose to be accidental.

Does anyone have any insights or similar experiences?