I'll always feel everything, the start, the "empty kill", the depression, the weight gain, the self loathing and his meeting with his mother which sets him on a road to recovery are all good and valid. And unlike others I don't think this tainted the character nor "ruined" him.
BUT... Because it's Marvel and because why do 5 jokes when you can do five times as many, they went too far with playing it for laughs so that the overall impression for some was that he was just a comedic relief. They can't see the dramatic arc because Marvel relies on comedy as a crutch and because the fan community themselves has vehemently argued that this formula is beyond any criticism for years. SOOOO... They didn't see an issue with having non-stop jokes around Thor's arc, even when talking with his dead to him mother. And again, they had precedent in not even taking how this could affect this drama because the previous Thor film is literally filled to the brim with humor that overshadows any of the movie's dramatic heft, what there is anyway. RAGNAROK has multiple moments that should be devastating to Thor on a character level. That stuff is either glossed over with zero weight given to what should be giant revelations to Thor (and all of Asgard really... How was all this kept from Thor anyway? Does that even make sense?) or the film just doesn't really care. In fact that's the issue. When you care about a story's drama things are given weight and consideration and there is a primacy given to a certain amount of consistency. But... When you wanna just get a laugh? None of that matters. Comedy is not only the death of dignity but since getting the laugh above all else IS the point, you can often times also chuck just about everything else away. And fellow fans... That's what they did in RAGNAROK, that's what the fans ate up and so many made sure that anyone that thought differently was shouted down online. And because of that, Hemsworth, Marvel, Feige and Co. and the Russos all thought tripling down on Thor's turn from Noble Warrior Prince to Dude Bro Meathead with a Heart of Gold was the way to go so that there was some character flying the flag of Marvel Studios brand humor amid the dramatic tale that was Endgame. (And before anyone chimes in... Yeah, there were other characters saying and doing funny stuff but Thor got the lion's share of comedic heavy lifting in this. More than Lang or Bruce or any other person on screen.)
Once more... I think Thor's arc is fine. And I thought his action scenes were awesome at the end. But in my opinion the issue that is dividing the Thor fan base is one that is:
1. Of their own making by accepting RAGNAROK's take whole hog with the mistake that said film "fixed" Thor, who did not in any way need fixing and certainly didn't need a comedic makeover which forsakes any other important aspect of the character.
2. Thor's arc was overshadowed by the Marvel Formula of adding superfluous comedy where it's almost NEVER needed. That's not to say not to have humor. It's that an EXCESS undercuts a legitimate super hero story. And it's not even something that comes from the source material. The level of humor in most character's books has always been dependent on the character. Spidey and Deadpool books? Humor should be there always. Sometimes a run will have a writer that can handle humor really well. When I read David's 90's Hulk it absolutely was a joy because he handled comedy so well. But that's not the only thing he did. He also delivered on great drama and characterization and that stuff was never cut off at the knees because of his comedy. Also, as I always say... I never bought a book because of the jokes. I never said, "Well... Gotta get this Month's Thor/Silver Surfer/X-Men/Capt. Marvel/New Warriors/Ghost Rider to see what jokes the writers have come up with." Not once. Unfortunately when it comes to MCU films about half the time they seem to put a lot more thought into how the comedy works over how the super hero story should. Thus we are left with films that about half the time work on the level of their humor but are kinda perfunctory about every single other thing.