It's inevitable that every new Android version comes with a few changes that some developers aren't too crazy about. One of the big ones with Android Q is "Scoped Storage," which essentially changes how apps can access the phone's external storage. Google was planning to limit all apps that don't abide by the changes introduced with Scoped Storage, but now they have backtracked on that a bit.
Before Android Q, any app could read or write any files to external storage (the files you can see when plugging your phone into a PC) if they requested the READ_EXTERNAL_STORAGE and WRITE_EXTERNAL_STORAGE permissions. You've probably noticed apps that clutter your storage with files and it was also a privacy/security concern. Scoped Storage aims to fix all of this.
Google planned to have it so that, by default in Android Q, apps only have access to their own data folder in external storage (located in /data/media/{user}/Android). To access shared media such as music or images, they have to request new permissions specific to those use cases. Apps that require broad access to external storage, like file managers, must switch from using Java APIs to the Storage Access Framework if they want to continue to broadly access the storage.
Developers have complained about this change as they felt that Google has not given them adequate time to make all the necessary changes to use the Storage Access Framework. And since Scoped Storage affects all apps running on Android Q, regardless of whether the app actually targets Android Q, developers had no choice but to update their apps. Otherwise, their apps will be broken when users try to use them on the next Android version.
The good news is Google has listened to feedback from developers as Android Q will no longer enforce Scoped Storage on apps that target Android Pie. Due to requirements to target recent API levels, new apps published to the Google Play Store after August 1st, 2020 have to target Android Q, while updates to existing apps published after November 1st, 2020 also have to target Android Q. All of this means developers now have until August or November of 2020 to modify their app with Android Q's new Scoped Storage in mind, which should be plenty of time to make the required changes. You can learn more about Scoped Storage here.
With input from Mishaal Rahman.