Looks like he was tapped by the car/driver behind him?
Any info on this?
He was being pushed from the back, intentionally, which is how he got to the lead. They got separated in the 4th turn, then got back together (either to push or with Newman blocking the loss of rear downforce, and that spun him out to the right. When the tires grabbed, the car took off to the right, into the wall, lifting the left side of the car off the ground, followed by getting flipped over to the right due to the relative wind. The car was skidding on the roof and the right side when someone else hit it, in drivers side right above the window. That appeared to severely distort the roll cage right above the seat and headrest. It skidded to a stop, caught fire briefly in the back, then skidded to a stop on the apron.
Pushing is not at all unusual, it is the fastest way to go, and aside from making the cars more prone to the problem demonstrated, not illegal. It's called a "tandem draft", and has been the fast way around for quite a while now. It's illegal in the other categories, in Cup, it's not, they just mandated some changes to make it too risky, both from an overheating standpoint, and because its easy to have what happened, happen.
When they first repaved the track, it was possible to run that way indefinitely, limited only by overheating, and it's probably 15 mph faster. If the bumpers slid relative to each other, no problem, if they stick/got locked together, the slightest sideways movement would almost always spin the front car out. The teams took to putting teflon tape or grease on the rear bumper so they would slide, that was outlawed, the tandem draft was outlawed for a while, then they changed the shape and height requirements of the bumpers to make them not line up, to that instead of a straight push, they would lift the rear end, causing a problem almost immediately.
As the track got bumpier, it got more risky, because the up/down motion exacerbated the problem. But on the last lap of the race, they were risking it, Newman took the lead via a push/tandem draft down the back stretch, got too far ahead of the pusher in the turn, and was rapidly losing ground to Hamlin and his pusher, so when Newman drifted back to his own pusher, the relatively high closing speed, and desire to try to block Hamlin on the outside and his own pusher, spun him out. More-or-less the same thing when Earnhart Sr. got killed, he was trying to block so Jr. and Michael Waltrip would have it to themselves, very similar crash into the outside wall.
This is the result of superspeedway racing. They used to have normal engines for Daytona and Talledega, until the speeds got out of hand (200+ mph unassisted back in the 80s, if you did nothing it might be 240 mph now), then a restrictor plate that cut the power from 800 on other tracks to maybe 450, and the unassisted speed is about 185 or so. Now they have a "tapered spacer" which serves a similar purpose and cuts the power everywhere. The loss of power results in a wild difference between a solo car and the draft, about 15-20 mph, so the cars run together for the entire race, in the draft. The last years worth of changes result in a much bigger draft and more rear downforce, which makes the effect of drafting much bigger, but overall slower (but still near 200 mph in a draft) and easier to slingshot past, and then get passed back when you are the leader. That's exactly what happened, he got pushed to the lead, the pusher backed off, with the idea of getting a run in the draft and passing him at the last second, they got together instead (either trying to push or trying to block).
The first 180 laps of the race were mostly uneventful because everybody just tried to avoid the accident, but this is the superbowl of stock car racing, and everybody tries to beat everyone else. This typically leads to massive multi-car accidents near the end of the races, there were two red flags in the last 20 laps, just like all the others.