The biggest new feature in the KDE Frameworks 5.81 release is the implementation of a new, custom hamburger menu called KHamburgerMenu, which will be shown on QWidgets-based apps whenever the main menubar is hidden.
The KDE Project plans to adopt the KHamburgerMenu for all KDE apps as it offers several advantages, including an alternative app menu in case you hide the default menubar by accident, more freedom when you want to take full advantage of the maximum vertical space, more compact design with only relevant menu items, as well as support for relocating, renaming, removing, or even changing its icon.