Hello,
I use the image_url and image_tag filters to have optimized images on the themes I develop.
When we give a high value of the dimensions, it generates a srcset attribute to optimize the media on different devices.
To take the example from the documentation (https://shopify.dev/api/liquid/objects#images 
{{ images['potions-header.png'] | image_url: width: 1000, height: 1000, crop: "center" | image_tag }}
renders
But when you add a height parameter, it is not changed in the srcset like this (I also added a crop):
{{ images['potions-header.png'] | image_url: width: 1000, height: 1000, crop: "center" | image_tag }}
this renders:
I think this is a bug in shopify so I share it and if there is ever a solution with these functions I am listening.