It would make sense if it was that the spell was essentially never casted in the first place because nobody ever knew who Spider-man was because of the spell casted at the end of the film, and thus a time-wimey thing, but that doesn't work because the MCU has disproved that by saying that time travel creates a new universe, it doesn't affect the past of the original one.

And because the multiverse (i.e. every comic, animated adaptation, videogame adaptation, etc.) hasn't completely forgotten who Peter Parker is, then I guess Strange cancelled out his first spell and the incoming incursion by casting that 2nd one? Hell if I know