On April 5, 2023, we will be updating mediaId Display & Video 360 API  for all uploaded Asset Creative 
What is changing? 
We are changing the ID space that is used to identify creative assets. This means that assets previously uploaded to Display & Video 360, such as image, video, and HTML files, will now have new IDs. 
This change will have the following effects:
Existing mediaId assets  Attempting to use any previously generated mediaId   
What do I need to do? 
In preparation for this change, we recommend that you stop using any cached media IDs when creating or updating creatives, and instead upload assets immediately before using them for creative production.
After April 5, 2023, we recommend updating any cached media IDs to the new values by retrieving them from associated creative resources or re-uploading them using advertisers.assets.upload 
If you are not caching media IDs, you do not need to do anything in regards to this change.
If you have questions regarding this change, please contact us using our support contact form .