In terms of reputable sources here are some must reads:
https://www.haaretz.com/israel-news/2024-03-21/ty-article/idf-releases-recording-of-army-spotter-killed-on-october-7/0000018e-623f-d541-a78e-ffffd4bb0000
https://www.google.com/amp/s/www.bbc.co.uk/news/world-middle-east-67958260.amp
https://www.google.com/amp/s/www.bbc.co.uk/news/articles/cg7825rk8j9o.amp
Israel had the plans of what Hamas was intending a year before Oct 7. Were warned again by Egypt days before Oct 7.
The IDF spotters at the border saw increasd hamas activity prior to oct 7 including hamas military training; efforts to knock out cameras, rehearsals for shelling of tanks, preparatory explosions at border.
From BBC -
In late September, an observer at Nahal Oz writes in a WhatsApp group of friends in the unit: "What, there is another event?"
A reply quickly follows by voicenote: "Girl, where've you been? We've had one every day for the past two weeks." The look-outs we speak to describe a range of incidents they observed in real-time in the months before 7 October, leading some to have concerns that an attack was coming.
"We would see them practising every day what the raid would look like," Noa, who is still serving in the military, tells the BBC. "They even had a model tank that they were practising how to take over.
"They also had a model of weapons on the fence and they would also show how they would blow it up, and co-ordinate how to take over the forces and kill and kidnap."
Eden Hadar, another observer from the base, remembers that at the start of her service, Hamas fighters were doing mainly fitness training in the section she looked over. But in the months before she left the military in August, she noticed a shift to "actual military training".
From Haaretz - female spotters from Nahal Oz and the neighboring Kissufim who survived the attack later reported that their numerous attempts to warn the army about unusual activity along the border fence were largely ignored in the days and weeks before Hamas' infiltration.
3 Surveillance balloons felled and not repaired.
At 05:30, members of the Golani prepared to begin a jeep patrol along the Israeli side of the fence - something they did before dawn every morning. But they were then instructed by their superiors to delay the patrol and stand back because of a threat of anti-tank missiles, three of them have told BBC.
It took over 3 hours for an IDF helicopter to arrive.