Change record status: 
Project: 
Introduced in branch: 
11.5.x
Introduced in version: 
11.5.0
Description: 

The DateTimePlus::prepareFormat() method is not used by Drupal Core or contributed projects. It is deprecated without a replacement.

The only thing that DateTimePlus::prepareFormat() does is it returns the $format parameter without any modification. If custom code is using this method, then it needs to be removed or replaced with a custom function.

Impacts: 
Module developers