Oldn, my interpretation of the report was that windshear caused the speed change. The Captain reported that the approach was stable, higher speed than normal, but then “increase within a second for 15kt (from 153 to 168kt)” a change most unlikely to be a commanded change in the thrust setting or vertical speed.
15kt/sec represents a gust, whereas aircraft are more sedate, approx max 3kt/sec, depending on type.