Popular LoFi Girl Instagram page is taken down with no explanation

Of course. Look at it from Instagram's perspective:

If someone tells you one of your tools is suspicious or could be a liablity for whatever reason, the most efficient thing to do is simply discard it.

From memory, the original image/clip was taken directly from a Ghibli movie, "Whisper of the Heart", but following a copyright complaint, it was replaced with an original work that was the same style and subject matter (a girl with her cat studying in her room, with a nice view out the window).

The visuals are original since 2017.

But the music which streams live on YouTube for ages I have no idea. Could be AI generated, could be original, could be stolen. The music (elevator lofi trip hop) is streaming for years without any interruption.