That’s a good question. As far as I can tell, a major catalyst was the 2013 movie adaptation of The Great Gatsby. That, paired with how we’re now living in “The ’20s” likely put the style of the 1920s on a lot of people’s minds.

Also yes, there is some overlap between the two styles and the use of seashell patterns is one example.

Some the images like the fan window remind me almost of the art nouveau images.