srcset attribute in Gutenberg gallery blocks

Gallery block are very useful to layout thumbnails. However, when I choose a columns layout (for example, four columns layout), the srcset for this thumbnail remains the same as a large image.

In other words, with a four columns layout, the thumbnails srcset come with:

sizes="(max-width: 768px) 100vw, 768px"

So, all thumbnails are built with the large images. For example, in this page: https://stage.margenesdelarte.org/productions/relato-de-salida-al-albergue-2018/

Is it possible to get something like this?:

sizes="(max-width: 768px) 100vw, 200px"

Further more, is it possible to set srcset up regarding the number of columns in the gallery block layout?

Unfortunately, setting the sizes based on the viewpoint size in the Gallery Block isn’t possible as of this writing (quite frustrating, imho) :/

There’s a couple outstanding tickets about this, notably:
https://github.com/WordPress/gutenberg/issues/9620 and https://github.com/WordPress/gutenberg/issues/13842