They also might be tracing, I saw this evidence on Tumblr. Don't know if you knew about this so *shrug*
Archived bc I'm not insane.
http://archive.is/IThVw (May 3 2020)
Compared to these drawings both before and after that one.
http://archive.is/lMupx (April 24 2020)
http://archive.is/1cdMV (May 4 2020)
http://archive.is/iCJUm (May 25 2020)
So yeah that's sketch.
This is just speculation, as we don't know the OG image (or if there even is one). Just thought I'd bring it up bc their track record already seems terrible. I could give them the benefit of the doubt and say maybe this is a base?? But why post just lineart of a base, that don't make sense.