How is Google using "Soften" add this effect to background images? [duplicate]

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• how to blur the background image only in css 2 answers

I stumbled across a blurring/softening effect that's being added to background images via CSS or Javascript. I'd like to replicate this effect on background images on my website, but when I look into the code on the Google My Business I cannot figure out how to duplicate this effect.

Any ideas on how to duplicate this? Blurred Image Background