No longer will you be able to have an unlimited amount of ads running on a Facebook Page at any time. What does this mean exactly for Facebook advertising agencies?

"In mid 2020, we are implementing a limit on the number of ads each Page can run at the same time. The ad limits will impact just a small percentage of advertisers, and we plan to share more details about the limits early next year.

We’re implementing ad limits because very high ad volume can hinder an advertiser’s performance. With too many ads running at the same time, fewer ads exit the learning phase and more budget is spent before the delivery system can optimize an ad’s performance.

To help you prepare, we released the Ad Volume API which allows you to track a Page’s ad volume for an ad account. In the future, this API will also track a Page’s ad volume across ad accounts and the number of ads that each Page will be permitted to use."  - Facebook

So what's the real reason here? Facebook is basically saying that the more ads that you run on your account, the less effective your overall performance will be. Their reasoning behind this is that they feel the more ads you run, the poorer the performance will be because your targets are already being hit with ads  that are already active on your page. This might provide the advertiser a negative experience with Facebook ads and ultimately looking to spend those funds elsewhere resulting in loss revenue for Facebook. 

Details are limited right now as to what the limit on ads will be but the assumption is that it won't be noticeable unless you are working on a brand with a large ad spend each month. Either way, this poses another hurdle for Facebook advertisers along with other negatives like a limit on ad accounts by a Facebook Business Manager and lacking reporting dashboards.