This degree of ridiculous power ups/creep really, really bugs me. This kind of thing happening this fast this frequently is such a bad decision. Can you imagine how bad this manga would have been if Deku had full usage of OFA by the end of the USJ arc, and then access to all the other quirks by the Sports Festival? Because that's pretty damn much what just happened with Shigaraki.
I still really like BnHA, but this is two feet in the grave, and about to start burying itself. This opens so many easy paths to ruin the manga. There's just too many game ending things in play, be it the quirk bullets (which thankfully got removed or reduced now), Shigaraki's unearned, contrived godlike power, Giganto-whatever-his-name-is, and so on. This kinda thing is a shounen killer. Why it never happened alongside the hero's powerups is a mystery and probably this manga's single biggest mistake. Aside from Shigaraki himself & the LoV being the main villains; these guys never should have been the main villains and have been outclassed by ever single new villain (group) in every arc.
In 3 arcs, Shigaraki went from 10%, to 100%, to 300% with at least one, and presumably several more equally broken quirks, and controlling an army that came out of nowhere. In 18 arcs, Deku has gone from 0%, to 5%, to 20%, to just now breaching 40% with 5-10% of some new quirks, and somewhat "controlling" a team somewhat analogous to pre-villain arc's League of Villains. This is the most insane powercreep bullshit since Naruto's jyuubi arc. Literally everyone except Deku, Eri and Eraser are effectively useless now.