No it doesn't work differently and the framing of all of this in the media is terrible. No one goes into making a movie planning on writing it off. They made a movie and decided that it was actually not going to be something worth releasing / unable to recoup the expenses, so they're not releasing it. This happens all the time with movies at all sorts of various stages of production. It just so happened this movie was "finished" before the decision was made. If they'd done this 6 months earlier than they did before it was "finished" no one would care.

They don’t spent the $90M intending to write it off.

This is a failure mitigation strategy where they failed and want to recoup as much value as possible.

Studios still lose $60M when they write off $90M they are effectively only saving the $30M they would pay in taxes. It’s still not profitable and they want to avoid this as much as possible.