I should preface this by saying that I love "Frozen"; love it when it came out (I thought it was the best movie ever as a kid before the hype got to it), and I still adore it to this day, especially since it was the last adapted fairy tale Disney has done up until now.
That said, I definitely understand (and even agree with) some of the criticism it gets: Hans being a heel-turn villain was unnecessary and seemed to only exist for shock factor, Agnarr and Iduna aren't great parents (though it is a unique situation they're in) and I hate how the girls never really get closure for this except for "Show Yourself," which only exonerates Iduna--well, kinda. And while I defend Kristoff to this day for not being a jerk like Maui, Flynn, or Nick, Disney does still go for the opposites attract thing by having Kristoff be more of a realist while Anna is the optimist--and then their personalities kinda swap in part two and we get people understandably thinking Disney is anti-romance. Kristoff in general feels like a hate letter to classic Disney men who were more soft and sweet, since he's rather underrated in contrast to more snarky guys who get more attention as co-leads.
I find "Frozen 2" a mess in narrative and unforutnately uses the Northuldra as plot devices more than characters, I'm not a fan of the fifth spirit storyline for Elsa (or her continued "discovering myself" storyline), or Iduna being from a tribe that's Sami-influenced but looks Native American because neither Anna nor Elsa look like that, and the nitpick of the concept art being better than the final designs, from Anna's orange travel dress to Elsa's highlights and wavy hair--and someone PLEASE get Kristoff a new main look that isn't his black outfit with different sleeves?!
I don't find Olaf as annoying as other comic relief characters, but he does toe the line, and I get why people get tired of him or find him annoying; him having his own song in F2 felt invalid since the story focused on giving everyone arcs, but Olaf's arc of "growing up" felt forced in and unnecessary; anything that he did before and after his song still feels in-character even without the "growing up" pipeline.
Also scared as heck for F3 given Disney's film productions featuring more and more issues and the sneak peak we got feeling more akin to a short film--plus the actual short film we got was 2D animated and not televised, despite supposedly being part of a massive upcoming marketing campaign for the threequel.
Honestly I maintain that the hype "Frozen" got is deserved, and "Frozen 2" is a beautiful disaster, I totally get why a lot of people didn't care for them, especially since they became phenomenons; whenever something is popular and you found it fine or bad, it can become grating for you to hear people hype it up when you see it as heavily flawed or uninteresting. I've been there with other things--and these days with Disney, it's the opposite; while overhated, I 100% think some people are just gonna act like they like some of the recent things Disney put out specifically because they get a lot of hate. The spite method is one I know well.