Disclaimer: I have no idea and it's confusing; I just read a bunch of stories just now; and people lie sometimes. That said, these are the details of the full plan as of a couple weeks ago, which supposedly came from Israel but which they immediately clammed up about whether or not they actually would agree to, not saying either yes or no for quite some time, which was weird. There is still some uncertainty over whether they will "agree to" their own proposal.

This is the best story I could find which actually somewhat explains what's going on at this point. According to it:

• Hamas didn't reject the deal but they asked for changes (details not made public and people disagree about what they were and how big they are). Personally I tend to put quite a lot of faith in the Qatari spokesman whose blackly comic summary of the issue was "two fundamental differences; between what Hamas wants as a permanent ceasefire, and what Israel wants as a hostage release and maybe a plan to continue the war."
• On that note, someone in Israel's government (no one knows who) said yesterday, "Israel will not end the war before achieving all its war objectives: destroying Hamas’s military and governing capabilities, freeing all the hostages and ensuring Gaza doesn’t pose a threat to Israel in the future." I.e. we get all the hostages back and keep killing you until we feel like we're done, and then at that point, we'll be happy to cease fire.
• We finally see the details of what's going on in Israel's government: Sounds like Benny Gantz (who already resigned) and Yair Lapid are supporting the cease-fire, and Bezalel Smotrich and Itamar Ben Gvir have threatened to "collapse the government" if it goes through. Nothing public about what Netanyahu thinks but Benny Gantz cited disagreements with him as why he was resigning.
• Both Blinken and Qatar are blaming both Israel and Hamas for doing too much bickering and not enough agreeing to the cease fire. Blinken points out, with maybe a certain amount of validity, that Hamas could have simply said "yes" to the US/Israel/UN/Qatari approved plan already on the table instead of giving the Israelis any room to blame them and keep the war going which is clearly what they wanted to do anyway.

TL;DR it's probably Israel's fault

It will. And in this time isreal keeps killing

That’s why Blinken is there. Hamas suggested an altered version of the ceasefire that Israel won’t agree to. Now Blinken needs to find middle ground.

https://www.reuters.com/world/middle-east/blinken-says-some-hamas-proposals-unworkable-work-ceasefire-continue-2024-06-12/

Israel needs to rebuild it

that might be directly related to "reconstruction of Gaza" thing

Read the sentence before it.

And if one side wants to continue the shooting and bombing? Then you can't even agree to a ceasefire. And that's the issue we have

This is the actual deal. It's been approved by the US, UN, and Qatar as a mediator. According to the US, it came from Israel, but there's apparently a little civil war going on in Israel's government about whether to "agree" to it or not. It seems likely to me that the terms were simply dictated to a mostly-unwilling Israeli government, then announced (by the US) "on behalf of Israel," and now they're pouting about it but also don't want to say out loud to their sugar daddy "fuck you I don't want to," because then we might stop arming them so comprehensively and vetoing things for them at the UN, and so they're stuck.

Hamas's proposed changes are not public, so it's impossible to say how big a deal they are or how necessary. I tend to blame Israel in general because they are so clearly acting in bad faith and also they're the ones killing all these innocent people, but... I also have to say that Blinken's statement makes some sense to me.

It would have been very easy for Hamas to simply agree to the deal on the table, and if Israel wants to reject it, or “accept” it but just continue the war immediately under some paper thin excuse (both of which seem highly likely), then at least there's not this weird confusion about whose fault that is. It's hard to come up with an explanation for Hamas wanting changes and fucking the whole thing up that doesn't involve blaming them for the inevitable results of that decision at least partly. To me as an unqualified observer person.

The Three-phase plan from the UN Resolution:

Phase one includes an “immediate, full, and complete ceasefire with the release of hostages including women, the elderly and the wounded, the return of the remains of some hostages who have been killed, and the exchange of Palestinian prisoners”.

It calls for the withdrawal of Israeli forces from “populated areas” of Gaza, the return of Palestinians to their homes and neighbourhoods throughout the enclave, including in the north, as well as the safe and effective distribution of humanitarian assistance at scale.

Phase two would see a permanent end to hostilities “in exchange for the release of all other hostages still in Gaza, and a full withdrawal of Israeli forces from Gaza”.

In phase three, “a major multi-year reconstruction plan for Gaza” would begin and the remains of any deceased hostages still in the Strip would be returned to Israel.

The Council also underlined the proposal’s provision that if negotiations take longer than six weeks for phase one, the ceasefire will continue as long as negotiations continue. No territorial change

In the resolution, the Security Council rejects any attempt at demographic or territorial change in the Gaza Strip, including any actions that reduce the territory of the enclave.