Facebook is making additional changes to their statistics. This time, the way in which Facebook calculates the organic page view is being adjusted. The goal is to reduce duplicate metrics and make it easier for businesses to compare results between paid advertising and organic reach.
The way these results are presented should be closer to the methodology Facebook uses for ads. This is not a change in distribution, but a change in the way you filter organic impressions. The change should not affect engagement and reach.
Everything will work so that Facebook filters out repeated organic impressions from the same person to reduce duplication. As a result, your site may show fewer organic impressions after the change.
The changes are expected to be implemented in late October. Facebook is now unable to predict how the change will affect individual pages, or if it will at all.