Wasn’t Potion Nova flying with wings in the previous scene while going into that cave?
 

 
Also, she had wings for the entire scene where she was talking about the world’s magic.
 

 
And I do mean the entire scene. This is not a single frame or a blink-and-you’ll-miss-it moment.
 
Animators just don’t care, looks like. But I still think it’s fun to say she’s an alicorn that hides her wings most of the time

@Inkan1969  
Besides Pony Life, Boulder also animated Rainbow Roadtrip, the Happy Birthday video for Netflix, FUNdamentals of Magic with Princess Celestia and most Equestria Girls’ Summertime Shorts. The Movie still was done in DHX Media/WildBrain!

My only guess is perhaps very early on and for a lot of the production of Pony Life (and the overall toy franchise that goes with it), Potion Nova was intended to be an alicorn. At one point higher-ups at Hasbro probably went against the idea of having her as an alicorn and made her a unicorn instead. At this point a lot of the animation involving her was probably done, so the studio might have gone back and made necessary changes to make her a unicorn. That would explain her wings appearing as often as they do and in cases like these where it would make sense for her to be flying.
 
Quick edit:  
Also, the delays. With showing off the show and the release dates being pushed back were probably because they had to give the animators for time to clean up Potion Nova’s alicorn animation at the last minute.

@Inkan1969  
They did do roadtrip but the movie was still done by DHX

@northern haste  
No, “My Little Pony: the Movie”.

@Inkan1969  
the cgi one?

@Background Pony #930C  
Didn’t Boulder do the animation for the movie and for “Rainbow Roadtrip” as well?

@Background Pony #3102  
Just to remember: This studio will animate G5. Don’t complain, ’cause it may get worse!

The animation quality is ridiculously bad. Like, how does someone get paid for delivering something like this?

I think the people making the show just couldn’t decide whether she was a unicorn or alicorn. That and/or they just give zero fucks about pony races, since the animators seem to just add and remove wings at random.

levitation spell?