All I know is that CNN for the first time(They said they would NEVER cover a Trump rally, he always lies according to them) but on that day, they covered the rally, from the start til he got shot, so yeah I think they had advanced knowledge of it. I think it was Plan B by the Biden Administration, off Trump, get Nikki Haley as the nominee, and have it as Biden vs Haley
CNN was in on the plan.
They knew what was going to happen.
Who tipped them off?
The reason/excuse they had for covering IIRC was the possibility Trump would announce his VP. Lame but that is what they came up with.