Before you break out the tinfoil hat, we need more info.
There’s too many details missing, and even a dealer will struggle to diagnose your issue.
These cars have adaptive cruise with speed sign recognition. When you pass a speed sign and it’s higher than your current speed it will increase the cruise control speed automatically by a proportional amount to what you previously set. I.e. if you were on a 60 road and set it for 80 when you get to an 80 road it will set to 100.
You can turn those features off and adjust how they act in the settings on the screen. It doesn't care if you're on an exit ramp or an freeway. And it doesn't always read the signs correctly. More than once it set my cruise to 70mph when I was exiting a specific service road. It just picked up the highway sign accidentally.
Also you cannot depress the accelerator and the break simultaneously for more than 3-4 seconds. The truck is programmed with a fail safe that cuts engine power when the brake is depressed if you still try to accelerate. It will do it above 20 miles per hour.
Some people have accidentally depressed the cruise control button on the left of the steering wheel, and that could absolutely result in an acceleration event unexpectedly.