By nod_ on
Change record status: 
Published (View all published change records)
Project: 
Drupal core
Introduced in branch: 
10.0.x
Introduced in version: 
10.0.0-beta1
Issue links: 
https://www.drupal.org/node/3269082
Description: 

Before the <details> HTML tag was available, Drupal had its own implementation of "collapsible fieldsets" for forms that later became the details render element.

All supported browsers now support the native details tag, so the supporting JavaScript is not needed anymore and will be removed.

Impacts: 
Module developers
Themers