Some core blocks that force a width on their content, currently don't set the proper attribute on images inside them. As a result the browser ends up loading images that are sized for the full screen width, rather than the actual width.

Affected blocks:

• Media and Text (fixed in this ticket but not the case where the block is inside a Column or another container)
• Columns (not fixed in this ticket)
• Post Featured Image (Query Loop, only fixed for the grid view)

For example if an image is in a Query Loop block displayed as a grid with 4 items, the browser will load an image that is 4 times as wide as it should be. It can easily lead to sending 10 times the amount of data, or even more.

There are a few options to modify image markup based on a block's column settings. In case of the Query Loop we can make the assumption that images will only be inside the post template.