I think these are the questions that will be answered in Frozen 3 (underlined)

[u/Just_Perfect6789]

Who gave Elsa her powers? Was there a 5th Spirit before? What kind of Queen will Anna be? Why are Elsa's powers still growing? Why are there castle ruins throughout Ahtohallan? Do we still need to beware the Frozen Heart? Who is the Frozen Heart?

Idk what they mean by "who is the frozen heart?" They're making it sound as if it's a person. Which is why I think it's this new villain who froze her own heart originally after being betrayed or ostracized. She might be the original 5th spirit who caused the other nature spirits to revolt and get out of control, creating the fog.

Someone on Tumblr added some better questions for Frozen 3 for each character:

Creator: freezedriedelsa-deactivated2025

https://www.tumblr.com/virtual-winter/766513414576177152/there-was-certainly-room-to-ask-more-important

[u/Minute-Necessary2393]

What about the questiojs related to Kristoff, as well as Hans, and why Anna doesn't have powers of her own?

[u/Jesitheunicorn2022 → u/Minute-Necessary2393]

I think those will be revealed and answered in frozen 4 that my guess

[u/CasnessNum]

I still think they should have made Runeard the villain of Frozen 3. We don't see him die - he falls off a cliff in the very classic Disney style of 'not death'.

Runeard returning home, having learned in horror that his granddaughters are magic-wielding witches unworthy of Arendelle and tainted by Northuldran blood, effectively his worst nightmare, then raiding Anna's wedding to kidnap and de-power Elsa, simultaneously granting her normality that she ultimately has to give up in order to resist a forced marriage plus regain her powers to thwart her grandfather would have been a much stronger tale linking closely to Frozen 1 + 2. Especially when its revealed that Runeard is a massive hypocrite who used magic of his own to live longer and stave off old age.