On death, certain items go back into inventory (as seen on the death screen in the hotbar) and fully disappear on respawn. In the provided example I lose the chestpiece on the first death, then the enchanted book (one of the two I've had) on the second one. Items don't have the Curse of Vanishing on them.

Video: https://drive.google.com/file/d/15otBr-4_QLmeBKUZyccCbDhPmvuvrG79/view?usp=sharing