Google confirmed changing Search Volume Reporting Method for KW Variants | αSEO(アルファSEO)

Google confirmed update on Google Keyword Planner in late June 2016.
Due to this update, search volumes for keyword (i.e. ”bag”) often includes search volume for similar keywords (i.e. “bags”), but not always,.
If you download search volume regularly, you can see large increases in search volumes for queries which have variants.