Hi Phil,
It is only missing from the label description on the back-end. The variable does exist, it is available for the live search end event (for other events the number is not yet known). This only works for live searches which does not involve results/archive/elementor page live filtering – only for the plugin results container.
I just checked, and it seems to work okay too, we use the default configuration, as the event label {phrase} | {results_count} and when I check the labels for the search_end events, I see the values: https://i.imgur.com/e3setlH.png
