Blurry Header Background Image

Site URL: https://www.hudsonvalleyrbern.org/

I recently updated our header background image with the attached file. I even resized it to the recommended 1500px. No matter what I do, the image is blurry. This is the first time this has happened and wasn't an issue when I updated to the winter photograph in September last year. Any suggestions? It's always been crisp in the past. 

I am having this issue as well. It doesn't look blurry in the Squarespace edit mode—only on the live site.

Have the same issue