Btn-xs style results in buttons that are too small

Some small buttons throughout the UI use the bootstrap class `btn-xs`. This class give them a very small button style. However, as seen in the notification tab, this is sometimes too small. The lower right button here has a size of 22*24, which is below the needed 24*24 to fulfill the WCAG 2.2 criterion SC 2.5.8: Target Size (Minimum).

Those buttons are expected to all have a size of 24*24 for a better accessibility.