The dashboard table of views can be resized to show the icons in 3 different sizes. Since Jenkins 2.454 the build button is no longer resized when the icon size is changed for the table. Also the size of icons is almost the same for table size M (20.8px) and L (22px)

The same effect can be seen for the settings button on the nodes overview page.

Culprit: https://github.com/jenkinsci/jenkins/pull/9131