It seems like Hestia does not take advantage of the srcset attribute as Neve does. We could implement this in future versions to improve responsiveness.

As mentioned before Neve uses it.

The feature request has been reported here: https://wordpress.org/support/topic/team-images-not-responsive/#post-15631100

This feature request was also opened previously with this issue #3