I'm pretty sure 5% have never felt from that height as well, and much less with two broken legs. Even Bakugo's smaller explosions can burn characters on his level so it's not like it really matter, and I'm not sure how this disprove Deku's rating 8-C+ when he is downscaling from Bakugo's durability, not his explosions.
That explosion calc is outdated and the result is actually way higher than that, so there's no point in discussing this paragraph.
Those landmines are capable of sending people flying several meters into the air at Subsonic speeds, just with that I got Wall level results, but the main point wasn't that, my point is that the feat is worthless and Deku hurting Bakugo and the 5% scaling is all that he has to gauge his Attack Potency, why are you even bringing this up?
If 5% actually did fall from that height, he would've survived with very little if not no damage at all. Any
8-C+ character could survive falling from a height like that at terminal velocity. This is a basic kinetic/potential energy situation.
"Even Bakugo's smaller explosions can burn characters on his level." Burning and actual force are two different things. Burning would be classified as durability negation since it's basically like fire. So that wouldn't really count. Not only that, Deku only
managed to stun him, nothing proves he actually damaged him, for the most part. He wasn't even really winded, just caught off guard.
How is the Grenade Bracer explosion outdated? I've recalculated it several times and can barely get above 4 Tons of TNT? There's no basis for this. Even if we assume it's outdated, it's stated to be Bakugo's full power but without risk. Like it or not, he was holding back against Deku, vastly.
When was is it stated, calculated, or implied people were sent at Subsonic speeds from the explosion? Even if we assume that each bomb is only Wall level, that wouldn't really make the bigger explosion
8-C or most likely
9-A+.
Even ignoring all the other issues backing up
8-C+ Base Deku (which is supposedly unimportant) your main point is somehow even more flawed due to the fact that Base Deku didn't really even damage Bakugo, more like stun him. So really it's faulty anyway.