Also. Guys, what happens in the fight can be very easily interpreted, just look at it:
https://www.youtube.com/watch?v=tKmqJk2NhQc
At first they are matching each other normally, with Ultimate Gohan vs Super Saiyan 2. Then here come the people say
"Oh, but if SSJ2 Goku is matching Gohan, he can't later match SSB, it's PIS!"
Yeah, not really.
They are both clearly holding back. Yes, they may look to be serious, but this is
very common in Dragon Ball.
Goku vs Freeza: Both opponents were holding back tremendously during most of their fight, yet by visuals alone they appeared dead serious.
Goku vs Cell: Both were sparring and holding back a lot, yet without dialogue you wouldn't tell.
Similar thing happens here.
At 1:25, Goku screams: "Gohan, release more power!"
So up until then Gohan was holding back.
At 1:45, Gohan gets more serious and hits Goku with a punch to the gut that by Goku's expression was really painful. Then he continues to beat the shit out of Super Saiyan 2 Goku.
At 2:00, after kicking Goku's ass, he says: "Get serious, dad!"
Goku does get more serious and they match each other briefly.
And at 2:20, he says it again: "Please get serious, dad!", and then quickly overpowers Goku again. Gohan powers up to 100%, indicated by the sudden aura he gains. He says "Fight me at full strength! At full strength! See my full strength!",screaming "This is my full strength!", to which Goku replies by going Super Saiyan Blue.
So no, Goku WASN'T holding back when he went SSB there. To suggest that he was would be to ignore the fight's
entire context.
At 2:50, we see the result of Goku and Gohan clashing, both at 100%.
Gohan punches Goku, then Goku punches Gohan again. Then Gohan exclaims again "At my full strength!", dashing. Goku punches Gohan, and it doesn't do
jack shit. Gohan punches Goku away, who goes Super Saiyan Blue Kaioken. And
only the does Goku stop being matched and surpassed by Gohan's strength.
Gohan with his Unleashed Potential
is universal. He
is stronger than Base Super Saiyan Blue Goku.
This is what's shown in the episode. Being Universal in Dragon Ball isn't special anymore. The supposed massive gap between tiers is not something that the plot cares for, and neither should you.
To suggest that Gohan simply can't be Super Saiyan Blue level is to ignore the entire context of Gohan Unlocking his Potential (Which Vegeta and Goku both stated in previous episodes is greater than theirs).
Gohan is Super Saiyan Blueberry level.