First of all Yuta never blocked a Granite Blast with peak output.
Granite Blast varies in output, shown as he can blast it before it gets to maximum output.
it questionable if the "reaching maxpower" wouldn't apply here as Ishigori can reach his max output in an increadibly short period of time its due to his CT that is focused on CE output being maxed out which puts the idea of the Granite blast that yuta deflected being lower on the output scale into question.
He can shoot a super large one, a very super thin one here too, and more.
yes but yuta did take that super large one head on
https://cdn.****************.com/file/CDN-M-A-N/tcbjujutsu/jjk176_010.pnghttps://cdn.****************.com/file/CDN-M-A-N/tcbjujutsu/jjk176_011.png
The only thing that we can argue here as to why Yuta didn't take quite as much damage as he did with the thinner blasts is due to area of effect, surface area and concentration of power, with the thin ones more than likely being more useful against singular opponents and with the huge area of effect one being more suited for multiple targets aka Uro and Yuta
Second of all, when he tried to punch one with a relatively smaller output, he got sent flying and part of his hand blew off. Straight blasted his fingers off and scorched half of his forearm.
you are forgeting a large caviat as to why yutas hand recived more damage here rather than before and that is because this:
https://cdn.****************.com/file/opctcb/jjk/jjk_tcb_177_008.png
and this:
https://cdn.****************.com/file/opctcb/jjk/jjk_tcb_177_009.pnghttps://cdn.****************.com/file/opctcb/jjk/jjk_tcb_177_010.png
happen back to back, meaning Yuta's hand was already damaged and here he literally it taking the granite blast point black meaning the surface area of damage is even further decreased meaning he is taking 100% of the granite blast without a possiblity of it being dispersed or redirected meaning the damage here will be at maximum output, also if you want to say that this granite blast was higher in output than the previouse one that would put your original point of varing power into question as here Ryu delivers higher output in less than a tenth of the charge up time of the previouse blast.
The only time we've got any confermation on a granite blast being weaker than normal output was here
https://cdn.****************.com/file/CDN-M-A-N/jjktcb_181_005.png
which is relating to this moment here
https://cdn.****************.com/file/CDN-M-A-N/jjk_179_tcb_012.png
which is related to CT burn out past opening a domain and would as such not be applicable to his regular blasts.
Also again we are talking about Ryu here his whole shtick is that his output is always on max setting be it during his punches or granite blasts
https://cdn.****************.com/file/opctcb/jjk/jjk_tcb_177_006.png
Rika blocked one and her hand got burned.
yeah it got burnt but it didn't get blown right off meaning there is reletivity between CT and CE reinforcement.
Third of all, Yuta and his ridiculous CQC strength could fight Ryu, but when Ryu got hit by the actual part of his attack, he got put on the ground.
again this fails to take into account that Ryu was severly damaged prior to this point
https://cdn.****************.com/file/CDN-M-A-N/jjk_tcb_180_006.pnghttps://cdn.****************.com/file/CDN-M-A-N/jjk_tcb_180_010.pnghttps://cdn.****************.com/file/CDN-M-A-N/jjk_tcb_180_011.pnghttps://cdn.****************.com/file/CDN-M-A-N/jjk_tcb_180_012.pnghttps://cdn.****************.com/file/CDN-M-A-N/jjk_tcb_180_013.png
and only after all this damage was he hit with the granite blast and that granite blast he was hit with took him by surprise from up above while he was focusing on yuta who was infront of him meaning that his reinforcement was more than likely weaker at his back than the front as it would make no sense to have an even layer of CE reinforcement when the only opponent you have left is right infront of you.
And before you say "Ryu took his own granite blast too", he didn't, it hit the part of the building right below em and still put him on his ass.
I mean I wasn't gonna use that one but its quesitonable if he was or wasn't hit so using that scan for anything is pointless before we get to see it in anime and know if he was hit directly or not
https://cdn.****************.com/file/opctcb/jjk/jjk_tcb_177_013.pnghttps://cdn.****************.com/file/opctcb/jjk/jjk_tcb_177_014.png
as can be seen in the first pannel the blast is seemingly going twards Ryu we even get that character reaction thing that most managa do when an attack is about to land on a person and they are surprised by it, but we see it hit the building as well so its kinda difficutl to say one way or the other.
Oh and yeah there is also this
https://cdn.****************.com/file/CDN-M-A-N/jjk_tcb_180_006.png
Ryu was able to flat out block and tank one of rikas blasts which was noted to possess a similar level of output to the granite blast to the point of being able to clash with it a few panels prior (although overall a bit weaker) and Ryu was able to no sell it with his hand