How has iOS 14.5 enhanced privacy and changed corporate advertising spend on iOS?

Apple has strengthened privacy in iOS 14.5, but this has made it a user's permission system for ``the app to track the user's behavior for displaying advertisements''. It is a specification change pointed out that it will give a big blow to advertising companies such as Facebook, but in fact, the marketing company Singular has released how the advertising cost for iOS changed.

iOS ad spend has been dropping since the release of iOS 14.5
https://www.singular.net/blog/ios-ad-spend-dropping/

Apple introduced a privacy feature called App Tracking Transparency (ATT) in iOS 14.5 that allows users to choose 'apps to use the user's advertising identifier '. Apps use advertising identifiers to understand user behavior and display ads based on their interests. For this reason, it is believed that not being able to use advertising identifiers is disadvantageous for companies.

According to Singular data, the introduction of ATT continues to reduce corporate advertising spend on iOS.

Below is a graph showing advertising costs (blue) for Android and advertising costs (red) for iOS among mobile ads. In the first week of February 2021, ad spend on Android was 56.16% of the total, and ad spend on iOS was 43.84%, almost evenly split. However, the difference in the graph widened over time, and in the week from June 14th to 20th, the advertising cost for Android was 70.29% and the advertising cost for iOS was 29.71%.

Based on the total advertising cost for iOS as of February 1, 2021, the total advertising cost for iOS as of June 14 has decreased to ``0.6 (60%)''.

However, before the release of iOS 14.5, Singular explained that more advertising costs were paid for iOS than usual. As a result, it is said that the decrease in advertising expenses for iOS seems to be large.

Also, according to Singular, 52% of iOS users have updated to iOS 14.5. There are also differences depending on the country, with 64.39% of all users in Germany and 63.77% of all users in Japan updating, but only 38.7% in South Africa.

As of May 21, 2021, worldwide iOS 14.5 usage was less than 20%. At this time, 19.4% of users allowed ad tracking by the app, but when iOS users increased to 52%, the percentage of allowed ad tracking rose to 23.64%.

The rate at which ad tracking is allowed, or opted- in, also varies by country. In the United States, where privacy enhancements are heavily advertised, the opt-in rate is 16.83%, while in Brazil, which is less advertised, almost 40% opt-in.