App designers are always trying to stay on-trend. The problem is that sometimes these trends tend to take design backwards from a usability perspective.
The last horrible design trend (2013)
A few years back when Apple decided to change iOS icons from filled in to outlined (in iOS 7), many believed this to be a step in the wrong direction, as outlined icons increase cognitive load.
The image and quote below are from Aubrey Johnson's analysis of the change:
Take a look at the example above. The red lines indicate areas where cognitive load is occurring. Your brain traces the shapes on the first row an average of twice as much. Your eye scans the outside shape and then scans the inner line to determine if there is value in the “hollow” section.
Forcing users to spend more time to decipher an icon is never a good thing, and unfortunately, many designers have followed this trend "because Apple did it", which is a horrible justification.
The latest horrible design trend