I'm having a similar problem as the above referenced post with blockiness in the map, but usually with the wind animations only covering part of the page.
It works fine If I don't include any URL parameters, but I get a a result like the following image if I include querystring parameters, like: https://embed.windy.com/?clouds,41.870,-75.476,5
Though they work fine in IE11 when not in an iframe. The iframe embed also works fine in Edge, Chrome, and Firefox.
I am stuck with IE11 for this application since it's for digital signage where the playback system uses IE11 for web content.