Are there any risks with the merge? Or is it a pretty solid and straight-forward process? For example could miners revolt last minute?

A bit of a noob and don't quite understand how the merge is implemented exactly if someone wanted to break it down for me more.

For example, if there will be no more mining after the merge, what's from stopping the miners from doing a last-minute revolt and cooperating? Could they do a 51% attack at the last minute?

Or is the merge pretty straight forward and no issues like this can happen. Just curious more how the merge works exactly.

Thanks!