KDE 5 had a feature in the keyboard shortcuts in settings where you could set a Window Action as a trigger instead of a keyboard shortcut (Documentation in the link). This means that KDE would do something every time a certain window appeared. This was very useful, my use case was changing the TeamViewer authorization prompt to NT logon as I don’t use the normal TeamViewer password. I think there should be a workaround if it’s truly gone, but for the life of me I can’t remember or search for the name of this software that does something every time a certain window is created.