After the releas of Moodle 4.0, the community has expressed their frustration and pain points regarding the activity icons being very similar in shape and color, making harder the scan-ability, distinction and understanding of them in the activity chooser and course page from both teachers/content creators and students perspectives.
The aim of the redesign is to improve the differentiation of the icons so users can distinguish between activities at a glance, providing different colors and highlighting the icon's shape against the container background.
Community feedback - Forum thread
Tracker issue linked -
New icons design proposal (Please note that the current display of all icons in blue is a temporary measure while the UX team works on finding the optimal color palette solution)