Earlier this month, Facebook announced that, starting in September, all Facebook ad campaigns - both new and existing - will be migrated to the platform's automated campaign budget allocation system, which aims to maximize ad performance by allocating more spend to higher performing ad sets.
At present, Facebook advertisers are able to set specific budgets by ad set, but the new system will remove that option, with advertisers only being able to set minimum and maximum spend limits at the ad-set levels. All Facebook advertisers will be receiving a notification on this - if you haven't, you can expect to see one in your inbox soon, providing the below overview of how the new system works.
The impact will be relatively minor for most businesses, but it is definitely worth noting either way. While Facebook's campaign budget optimization system theoretically enables businesses to more effectively allocate their budgets to maximize performance, it is also based on Facebook's systems, which means marketers will need to have some level of faith that those processes are optimizing for their goals.
The truth will be in the results, of course, but it is a relevant consideration to keep an eye on. For more information you can read about Facebook's Campaign Budget Optimization here or specific detail on ad set limits and controls here.