Does it seem like the older La Reine des Neiges gets, the plus populaire Anna gets and the less populaire Elsa gets?

Online- yeah, I totally get what you're saying. People are starting to look at Elsa without the rose-tinted glasses and see that her character has a lot of issues, and Anna is starting to be recognized for her multi dimensional personality instead of being thought of as the "useless" sister, which I am so here for.
Outside of the internet, though Anna is getting a bit plus l’amour (and par a bit, I mean a tiny bit), Elsa still reigns supreme overlord of young children and non-disnerds, so her popularity hasn't gone down (at least from what I've seen). Only strong La Reine des Neiges haters seem to dislike Elsa, but they also hate on Anna, and a lot of times don't even know her name.

I didn't see La Reine des Neiges until about a an ago, so I missed the early months of the fandom where Anna got hate (I find it hard to believe there was a time when she got only hate!), but when I came into it Elsa was still much plus populaire than Anna. I don't really get involved in the fandom outside of Fanpop, so I don't know whether the Elsa fans are still active in other places, but here I've noticed it too.

Can't say I've noticed Elsa getting much in the way of hate (with the exception of maybe one ou two fans here - the majority don't seem to have an issue with her) but I have noticed Anna gaining plus and plus positive attention.

That said, I think Anna has been a plus noticed character among older fans for a while. Teens and adults seem to at least quote Anna plus when talking about La Reine des Neiges (even if she isn't their favourite, she is clearly a memorable character to them all) whereas when I've done cover work at pre-schools I've noticed that Elsa is still the favourite among 3 to 4 an olds! So I definitely agree with toi that this is a thing that's happening mostly with the older fans.

Elsa COME BACK

Yes! Elsa is important, but, Anna keeps on getting plus popular, and I hate that. I think, the reason why the movie is called 'Frozen' because of Elsa! And a lot of the time, I see people saying 'Anna' instead of 'Frozen'! It's dumb!!!