One more reason to think mobile first
Starting with 2018, Google is indexing the websites starting from the mobile version, as opposed to the previous algorithm which used the desktop version.
This means that the mobile version is the one to consider for indexing and displaying search results.
For agencies and clients this involves changing some mindsets, as most designers are used to create for larger screens and most clients are used to approve the desktop version with lots of visual elements (90% of their focus) and just briefly revise the mobile version.
Photo: Google Images search