A couple of screen shots below show a difference which has me stumped.
The only difference between the two screen shots is an additional page filter:- include URLs containing somesite.co.uk
Why is it reducing the metrics since Google's note (see link to it below) as there's no query filter applied in either screenshot?
Observations, notes, info:
Previously adding the page filter increased the Impressions, Clicks, etc metrics, still evident in the above before Googles note. Now, it reduces Impressions dramatically (in this example) post Google's note.
I never confirmed why adding the include url containing somesite.co.uk page filter increased the metrics previously, but had a theory it was probably around searches with query info and searches without.
Google's note dated 19 August 2018: Chart totals no longer include anonymous* (rare) queries when you apply a query filter.