Glad that helped solve the issue, but for some reason I’m not seeing the high quality images on my end:
In terms of whether this is expected behavior, I can’t really say since I don’t have much experience working with Grid. It’s possible this is a bug when responsive images are spanning multiple cells within a Grid element which may be more to do with the JS library that’s powering the automatic responsive image feature.
That said, I notice another user having the same problem just yesterday so I’d probably recommend shooting a quick email over to Webflow Support so they are aware of the issue. You can either follow the link below, or it can be done directly in the Designer by hovering over the question mark icon at the lower-left, then clicking Help & Feedback, then the “Send us feedback or a help request” link