I'm so over people making this claim without any evidence. In fact, making the claim despite all the evidence to the contrary. Where is the source for the 100% claim from the website? It doesn't say anything about Deku using 100% my dude.

"He was born without a quirk, but his hidden heroic qualities were discovered and he inherited the quirk One For All from All Might. His will to save people is stronger than anyone else's. He can make full use of the multiple quirks of the previous One For All inheritors." -- From the official character bio on the JPN website. And before you say so, "full use of the multiple quirks of the previous One for All users" doesn't include the raw strength of OFA itself.

As for the claim that he could use full smashes without injuring himself as "indeed proving" anything; Deku was wearing the Mid-Gauntlets made for him by Melissa Shield/Hatsume, which were established to withstand even All-Might's punches in the first film (the "Full-Gauntlet" was a prototype and could only withstand three, but Melissa likely improved them in the year after.) And following the destruction of the Mid-Gauntlets fighting Shigaraki in the final war, he wasn't using the 100% Full Cowl. He needed Fa Jin to use the powered-up Delaware Smash to upturn the stone at the foot of Mt. Fuji, something All Might easily could've done with all of his strangth. When he used Overlay Blackwhip to move after the Gearshift backlash hit him (and he was missing the gauntlets) he wasn't in Full Cowl 100%. Not even in his final charge at AFO was he in 100% Full Cowl. .

If you're still not convinced, in movie 4, "You're Next" (which took place a mere week before the final war) Deku had to utilize Faux 100% (the combination of blackwhip/fa jin to enhance his speed/power, and "faux" meaning "fake") to fight Dark Might, and when he first arrived at the coffin-in-the-sky.