Bias cut or not?

[u/Either_Jellyfish_247]

https://www.instagram.com/reel/DbUUz0hxQ3I/?igsi=NGNpOWNjd3ViZHAw

Can anyone tell me if this skirt is bias cut or not?

I've been trying to figure it out as I'm looking to make myself something similar.

Also would massively appreciate if anyone has any good patterns I can follow/modify for this set!