The Twitter account of Israel (MFA) has [archive link, the original tweet was deleted] this slightly odd claim:
Hamas accidentally posted a video of a doll (yes a doll) suggesting that it was a part of casualties caused by an IDF attack.
For the NSFW weary: the video depicts a child- or adolescent-sized body, wrapped in a white sheet with some blood on its face, but the face has a rather waxy color. The body is being handled in a hospital setting both inside and at an entrance. (Possibly this might have been a training exercise?)
I've been unable to find more detail on where Hamas supposedly released that and what they actually claimed. As for that being a doll, I'm not 100% convinced either, from the rather low-res video. (Sometimes embalmed bodies do have a waxy color. But in that case, it normally shouldn't have blood too.)
So, given the number of western-outlet journalists on the ground in Gaza (and which often take footage in quite a similar setting at hospital entrances and even inside), is there confirmation or infirmation of this story from some other sources that don't simply repeat the Israel MFA (there's plenty of those, be sure)?