Undo/Redo in all plugins. See FabFilter and Waves for reference.
Shouldn’t plugin vendors implement undo/redo capabilities themselves?
This is referring to the steinberg plugins that come with Cubase. FabFilter is a good third party example that includes undo/redo in all their plugins.
Maybe. Or at least it would be nice.
This topic has been discussed in a few threads. There was a version iirc C12 when using Mix History Undo, undo worked for 3rd party VSTs.
That, unfortunately, was a bug and removed. Ironic right?
The issue has been reported to Steinberg. Keep in mind for future reference, there are different Undo’s in Cubase. Another type of undo, which has frequently been requested to bring back is Key Edit otherwise known as Local Undo.
Why removed is another topic. Until then, yes the VST undo if available is your friend.