What happens when someone unclean from one of these things mentioned in Numbers 19 touches something?

Answer From The Annual Reading Schedule - Week 36 Notes For Numbers: It's unclear what happens, if anything. In the past I thought Numbers 19:22 may have been saying that the thing they touch is unclean, and anyone touching becomes unclean, but now I'm wondering if Numbers 19:22 is actually talking about the one who does the sprinkling in Numbers 19:21 instead. See below notes for more comments about this.