I've never heard of russians purposefully shelling territories that they occupy at the moment. The only instance that comes tomind is them accidentally bombing Donetsk city last year, but I don't think they used cluster munitions.
I guess what they meant in the podcast is that russians use cluster munitions without any regards for the future, as their munitions have ~30-40% fail rate. Meaning that 30-40% bomblets don't explode, but will remain on the ground until demined, or somebody stumbles upon it.