The previously used 
is a Unicode symbol and had to go because its look depends on the available system fonts and it can’t be styled to fit with Anki’s theme.
We could replace it with a more similar SVG icon, but the grid one usually represents the internet or networks. The earth icon seemed less amibiguous for representing global.
In fact, I think very few users will be able to guess the meaning from just looking at any icon. So I’ve added a tooltip and chose a more distinct icon that is less likely to appear in other contexts.