Thank you for this. I noticed that there are no photos or other material that show any of the restraints, just the closed body bags with Hebrew tags. You would think that they would immediately photograph or film such restraints, but for some reason, they did not and they are only mentioned in the article text in both this article and the Al Jazeera source. The article on Al Jazeera's website, which includes a video overlayed with ominous music (not something a reputable outlet would do), includes the lie that the men stripped and restrained for processing a while ago were out in the cold, even though one could easily access weather data for Gaza that showed it wasn't cold at all at the time.
From a logical perspective, it would make no sense for Israel to leave the bodies behind with restraints, whereas burying bodies they come across is perfectly reasonable for the purposes of preventing disease. If the goal of this burial had been to hide executions or a massacre, then they wouldn't have tagged them, which would place the blame entirely on them.
The most reasonable explanation, in absence of more concrete evidence, is that these are either civilians found in the rubble or killed in the crossfire - or Hamas fighters who died in combat. They could also be people killed by Hamas (who just murdered a pro-peace activist after abducting and torturing him). I think what happened here is that IDF cleanup crews buried these people, likely without identifying them beyond checking if any hostages are among them, and now returning Palestinians are exhuming the bodies again in order to find missing relatives.
I also have a really hard time believing random unnamed eyewitness reports of mass executions. Given the enormous prevalence of smartphones and their extensive use to document this conflict, one would expect that an act this significant, this unquestionably monstrous would be filmed. It would be the single greatest rallying cry for the Palestinian cause imaginable. Watch any video of the aftermath of a bombing raid in Gaza and you see more people with cameras than people trying to help the wounded. If a random Belgian with a bulky camera can secretly film executions of civilians by German forces during WW1, then surely so can Gazans with much more readily available, much more concealable smartphones.