In brief
background-blend-mode controls blending between background images and the background colour. This allows a photograph to be tinted through layered backgrounds.
Useful to know
background-blend-mode controls blending between background images and the background colour. This allows a photograph to be tinted through layered backgrounds. [1]
An element's content is not the same as its background layers. Blending text with everything behind it is a different task. Also check the fallback appearance when an image is missing.
Sources
For further detail and to check the information: