MC: Memory Link -> Forest of Thorns -> The A-class Cannon -> Green Lightning -> 8 Scythe at the same time -> Body cleaved in half -> Cool Power Armor -> Fighting the Immortal Monster -> Stretching
Alice: Max power Minute Collapsar -> Dozens of Dark Graviton Bomb -> Miniature Collapsar -> Reverse Gravity -> Dark Graviton Bomb
Liz: badly wounded by an A class (she's a level 1), but still has power probably
Deryl: didn't run out of power
Michael: HUNDREDS of corpses, at least one including S class
I believe that the MC lost his power, since lightning and stretching has always been stated as extremely energy consuming to resist and do respectively. Alice you may argue that it was a bit weird, won't try to deny it, but we also have to consider that the Sky Attraction has been stated since the beginning as irresistible if you try to fly, so only option was MC. Overall I don't think of it as a Deus Ex Machina or anything similar, more like a way to pave Michael's evolution, since he ingested the S class power. Could it have been done better? Yes, most times everything can be done better, that's the curse of writing. MC is stronger now? Yes, but everything he does in the previous major fight (Cole) was less energy consuming and grounded, except after MC started using Deryl's stone, and MC loses his power just after that.