It had once been rumored that the Mjolnir Jane Foster uses in Thor: Love and Thunder is from an alternate timeline that the Loki leading the upcoming, same-named Disney+ series brings over, but I’d argue it’ll be even more interesting to see the original Mjolnir reform simply because it detects Jane’s presence and deems her worthy.
However, Cap later returned the past Mjolnir to its proper place in time, and Thor seems quite comfortable continuing to use the Stormbreaker axe.
Avengers: Endgame provided an opportunity for moviegoers to see Chris Hemsworth’s Thor use Mjolnir again when he retrieved a past version of it during the Time Heist, which paved the way for an even bigger moment: Captain America using the hammer during the climactic conflict against Thanos.