This. Facebook makes available a lot of configurable parameters around bidding and budgeting[1]. If you've set a campaign-level budget, Facebook's system paces

This. Facebook makes available a lot of configurable parameters around bidding and budgeting[1]. If you've set a campaign-level budget, Facebook's system paces delivery to spread that budget from the start date to the end date. It automatically adjusts pacing to fluctuations in delivery, this 6 hour outage is just a drastic version of that, where there was zero delivery across the board vs. more localized fluctuations in consumer behavior that usually impact pacing for individual advertisers. So it has to accelerate delivery for the remainder of the campaign to compensate, and since it's doing that for all ads with this type of budgeting configuration it's resulting in an auction grab for available impressions and temporarily bumping up CPMs as a result. Which isn't necessarily a positive for advertisers, but sounds like their system doing what it normally does, and just having some unanticipated second order impacts when faced with an extreme event (compensating for global lack of delivery for 25% of an entire day). If your budgeting/bidding/optimization configuration doesn't require a specific spend within a specific timeframe, you're not going to see this sort of acceleration. But you will see higher CPMs due to the increased auction activity from others having their pacing accelerated. And they weren't collecting FB pixel data for 6 hours either, so conversion activity will also be underreported and show higher CPAs. But CPA-based optimization configurations are still in place and doing what they normally do, and frequency caps if you use them are still limiting how many times your ad will show to the same person. So even those seeing accelerated delivery and not wanting to could adjust their ads' settings to avoid it. > The "accelerated delivery" that Facebook quoted in its response only applied to the remainder of the day that the outage took place -- not future days as the article suggests. It does actually impact future days, just to a far lesser extent than day-of. Pacing jacked up the day of to attempt to compensate for expected pacing that day, but for those that didn't achieve it they'll continued seeing accelerated delivery beyond that to hit the spend target by end of campaign. Plus second order effects as their optimization see-saws around until things settle back down. [1] https://www.facebook.com/business/help/1619591734742116 https://www.facebook.com/business/help/1619591734742116