Thor goes through a tremendous arc in Avengers: Infinity War where he had fluctuating power levels throughout the whole film — here’s why.
Thor’s power level fluctuated continuously in Avengers: Infinity War, and it may in fact have been for a very good reason. The God of Thunder was coming from consecutive tragedies by the time Thanos appeared in the MCU. Coming off from the death of Odin and the destruction of Asgard in Thor: Ragnarok, Infinity War piled up on that by having Thor be quickly neutralized so he could then helplessly watch the death of half of his people – including Loki and Heimdall’s deaths at the hands of the Mad Titan.
He was almost dead before the Guardians of the Galaxy found him floating in space, but during his trip to Nidevellir, he seemed to be in top shape again, as he’s able to directly take on the energy of a full star. Thor held up long enough just for Eitri to forge the Stormbreaker, after which he was once again knocked out, but by the time he arrived in Wakanda, he appeared to be stronger than ever. These fluctuations were confusing for viewers, but looking more closely at his arc in Infinity War coupled with additional information from its writers, Christopher Markus and Stephen McFeely, there’s an explanation for all this.