I honestly don't understand the surprise. For one this new form isn't even new, but something clearly halfway to his Superman-Prime gold evolution.

As for what may have caused it… We don't know if Superman gets rid of his Red Levels or not. And as we know the combination of different isotopes of kryptonite have different effects from what is seen with just one.

Also this "new" power, seems to be nothing more than what we saw in The Final Days of Superman. When a human infused with the Flare power of Superman, became able to turn into a gold Superman with all the powers of Superman but none of the weaknesses.

And for all we know, the effort simply unlocked a more evolved version of the Flare power. Something we've already seeing also with Superwoman (Lana Lang). Only her form is red instead of yellow, mainly because she got her powers partially due to red kryptonite.

We already knew he's going to fight it off and perhaps it will even be the trigger for Superman recent change seen in Superman: Unlimited. Where Superman changes halfway to his Superman-Prime gold form.

Hock73

Gunn cleverly knows what he's doing. He has broken bones, when they heal, it hurts.

But that's the thing. Even in the comics when Superman had a broken arm or metal piercing his body, he would heal and not show any pain.

Superman even regrew an entire hand after Luthor tried to infect him with green kryptonite nanobots, without showing any pain.

Do you know when he felt pain? When his body had absorbed too much energy from radiation, and then when exposed to sunlight his body would forcefully remove the toxic radiation.

Even in Superman and Lois, when Superman powers are drained by Ally and he needs to jump start them by being thrown into the sun. We see that Superman was in terrible pain only at first because his skin was actually burning, but as his cells returned to normal the pain was gone his healing factor was working again.

That's following the comics and not what Gunn is doing.

He could have remnants of Kryptonite in his system that is being burned out of him, even if we don't see it.

Thank you for showing you also don't know that much about the character. When Superman was infected with a green kryptonite cancer, his whole skin turned green and he was weak and in pain, but as soon as John Irons gives him the equivalent to amped sunlight, he was again fine. No pain in the recovery.

Both he and Kara have said it in the comics multiple times, that unfiltered sunlight makes their bodies less vulnerable to kryptonite, because it nullifies the radiation faster in a painless way.

So, again. James Gunn doesn't enough about the character. Not to mention the whole scene is dumb for the reasons I've already pointed out.

Add to that Gunn and the whole cast poor performance at CinemaCon, and you should be very worried.

Gunn even said he was very happy to be at ComicCon, TWICE! When it was at CinemaCon. And then he went on ramblings that had almost nothing to do with the movie.

Oritsegbubemi

You mean the famous Recovery Suit. And no, he was not "basically a normal human" because like I pointed out he tanked a full power heat vision from Jon and it did almost nothing.

And Jon if you well , at the end of Dark Crisis, he was fighting Anti-Life Darkseid, Doomsday, Neron and Ares. So, Jon isn't weak. He simply isn't as powerful as Superman.

Even all the hype that DC tried to sell about his energy powers, didn't matter at all because not only the Phaelosian (Kryptonian) adopted twins Osul-Ra and Othol-Ra can use energy powers and even shape that energy into weapons, but Superman himself showed he can use that energy manipulation as well.

And so, even the one thing that was supposed to make Jon different and better, was shown being better used by the adopted twins of Clark and Lois but also Superman himself.

Even now in the Secret Six comics, things that Jon could've and should've used his energy powers on, weren't used at all. Because when Superman went through those powers back in 1998, he eventually learned to use them to even fight magic and other bothersome powers.

It's like DC just doesn't know what to do with Jon. To the point that the whole Dragon Ball talk of Jon having more potential than his father just because he was human, was slowly but eventually dropped altogether.

Actually this was not the only thing that proves that Superman is far more powerful than his son (Jon).

In Absolute Power when Jon was already a cyborg being controlled by Brainiac Queen, when he breaks into the Fortress of Solitude. Superman that just had surgery and was still recovering from the power drain, takes a full power heat vision blast from Jon and it does nothing to him, except stun him a little bit. And Jon wasn't holding back one bit.

As for Jon growing out of his weakness to kryptonite or becoming more resistant to it. If we go by what Future Frontier showed, not only will Jon never become less vulnerable to kryptonite, not only will red sunlight actually become fatal to him seeing Solaris high dose of red solar energy starts destroying Jon's cells, but when Jon is apparently already dead his half-brother Pyrrhos is quite alive and a huge problem to the descendants of Jon and Kara.

However when a then older looking Superman shows up, not only does he takes down Pyrrhos with one single backhand slap, but Pyrrhos magic doesn't do anything to Superman. The same magic that easily took down Kara Zor-El.

That older Superman saying he had returned from fighting a huge threat in another dimension. Revealing he had been away for centuries, fighting.

I'm starting to believe the rumors of the bad screen testings more and more.

So, the robot says they have no consciousness, but they give gender to a genderless machine, that acts all happy when it sees that Superman looks at it.

Funny how for something that doesn't have consciousness, it sure acted like it had one.

And then, all that Kryptonian advanced technology and what do they use to heal Superman… The equivalent to several magnifying lenses to focus the sunlight.

But the bad scenes don't stop there. Seeing what should've brought comfort to Superman, brings him pain. Which is nonsense seeing even when Superman gets heavily dosed with kryptonite, receiving extra sunlight doesn't hurt him but instead invigorates him.

Even the Fortress should have like a fusion reactor and the recovery of Superman, would've been the robots redirecting energy from the reator to Superman, giving him the equivalent to a miniature sundipping effect.

Gunn clearly doesn't know what he's doing. He's clearly focusing not even on Kingdom Come Superman, but the old Bronze Age Superman. Where things like magnifying lenses were something he used to get solar boosts.