In Thor: Ragnorok, Mjolnir was destroyed by Thor's sister Hela, and up until Thor: Love and Thunder, he had been fighting with Stormbreaker, an enchanted axe forged in Nidavellir. While Stormbreaker is an excellent weapon, Thor makes it clear in Love and Thunder that Mjolnir is his favorite.
In a moment of wistful affection for his girlfriend, Thor asked his trusty hammer to always protect Jane, and in doing so unwittingly enchanted Mjolnir to do just that. Just like Thor's father Odin once enchanted the hammer to only be lifted by someone who is worthy, Thor cast a spell that let Jane use its powers.
The most likely explanation for Mjolnir's return in Thor: Love and Thunder is that it's been repaired, as the hammer Mighty Thor wields in footage is webbed with bright blue cracks. Given Thor's surprised reaction to seeing Mjolnir (and Jane), this repair probably didn't happen at his request.
The short answer is yes, Thor is still worthy of lifting Mjolnir after Thor: Love and Thunder. His worthiness comes down to the reason why Mjolnir chose Jane. In the comic books, Mjolnir does choose Jane to be Thor after Thor becomes unworthy and is unable to lift it.
Mjolnir is a hammer, and was enchanted by Thor's father, Odin, so that only those the hammer deemed "worthy" are capable of wielding or even lifting it. Stormbreaker is an axe, and although it does not have such a worthiness enchantment, its power is such that a mere mortal attempting to wield it would be driven mad.
But Nick Fury, always prepared, had a way to take out the do-gooders. In the case of Thor, all it took was a whisper of the simple phrase, “Gorr was right.” After hearing this, Thor was unable to wield Mjolnir. He was rendered unworthy, because in his heart he believed what Fury said was true.
Although Stormbreaker and Mjolnir have very similar properties and powers, Stormbreaker is the most powerful weapon wielded by Thor so far. The obvious reasons are that Stormbreaker is the physically larger weapon out of the two, and not to mention that it is an axe, which could well be more dangerous than a hammer.
While the primary Thanos from Earth-616's universe was defeated and was never worthy to lift Mjolnir, it's possible that a future (or existing) variant of Thanos could.
However, the film also implies that the hammer only sees Jane as worthy because Thor unintentionally revised the rules of Mjölnir, giving it the power to protect her. Captain America didn't need anything special for the hammer to see him as worthy – he's able to wield it without issue in Avengers: Endgame.
First and foremost. Loki simply isn't powerful enough. He may have tricked a weakened Odin. But he still clearly wasn't powerful enough to override the worthy enchantment or do anything to that hammer or Thor for that matter.
In one notable modern storyline, centering on Thor's relationship with Mjolnir, the God of Thunder lost his ability to lift the hammer after becoming convinced that humanity doesn't need its gods, robbing him of his divine purpose.
In the comics everytime Jane became Thor, Mjolnir purged her body of toxins. In her case those toxins were the chemotherapy drugs that were at the very least keeping her cancer in check. So everytime she became Thor her condition became worse.
When Thor and Jane are still dating, Thor asks Mjolnir to always protect Jane no matter what. This oath alone speaks to the deep connection between Thor and Mjolnir, which rarely finds others worthy of wielding it. To keep its promise to Thor, the hammer calls to Jane telepathically, guiding her back to New Asgard.
Across multiple comic continuities, Thor has had several daughters including Brigid Thorsdottir, Thena Thorsdóttir and Torunn Thorsdóttir, the latter recurring in many iterations. In Norse Mythology, Thor had a daughter named Thrud with Sif.
The simple answer is no. Yes, Hulk absolutely smashes Thor to the ground with Mjolnir, but, he's holding both Thor and the hammer. Hulk wouldn't have been able to lift Mjolnir by himself, but since the God of Thunder had a firm grip on it as well, he was able to use it as a weapon against his teammate.
Without the Infinity Gauntlet, Thanos stands little chance against Prime Odin. Odin is stated to be able to shatter the Earth. And he turned Frigga into stars. He has devastated while worlds, laid waste to kingdoms and destroyed demons and monsters.
Loki is confirmed to be worthy of lifting Thor's hammer, Mjolnir, for the first time in official Marvel canon. In The Immortal Thor #5, Loki confidently catches and wields the hammer, showcasing his growth and heroism.
The movie doesn't explain Thor's motivations for giving up Stormbreaker, but it makes sense that Chris Hemsworth simply wanted Love to have a powerful weapon to aid her in battle. It's unlikely that he could give her Mjolnir, considering that so few people in the MCU have been deemed worthy of its power.
Unlike Mjølnir, however, the weapon is not enchanted to prevent those deemed "unworthy" from holding it, making anybody with sufficient strength capable of using the weapon.
It wasn't until 2016's Unworthy Thor #5, by Jason Aaron, Olivier Coipel, Kim Jacinto and Pascal Alixe, that Thor finally revealed that the words Fury had said to him were simply, "Gorr was right."
This arguable arrogance may have also contributed to being unable to lift Mjolnir. Likewise, the Hulk was, at the time, a rampaging beast, lacking much else in the way of personality. Thus, he had no morality or sense of justice, being ethically unworthy of Mjolnir's might.
In the former movie, it was likely Tony's narcissism and lack of humility that contributed to his “unworthiness.” These attributes did, however, make him a hero. After saving the world, making a play to sacrifice himself, and defeating Thanos' army, he was not able to lift Mjolnir in Age of Ultron.
