Hello, it is sometimes that I have this behaviour:

when I use repeatedly a zle widget like kill-word and then I use yank to restore the killed text, only the last killed word is returned.

I remember that all the consecutive killed word were returned at once, and the manual support this: 

[...] When repeatedly invoking a kill widget, text is  appended  to  the  cutbuffer instead of replacing it[...]

Is it possible I deactivated this behavior somehow?

the manual says also "when wrapping such widgets, it is necessary to call `zle -f kill' to retain this effect" but I am not wrapping them