Yes, there can be some drawbacks to blocking an app’s telemetry data. To start, blocking telemetry data can cause interference in some apps, based on their device, their version of Windows, the version of the app they’re running, and more. It can also hamper a user’s experience on an app they’re using since it removes personalized ads.
On top of that, Windows flagged modifying telemetry data as a severe security risk. This is because the automated process that brings error codes and the like Window’s attention is prevented by blocking telemetry data. While Ashampoo AntiSpy lets you modify how much data you want to be blocked, blocking all telemetry data can cause these problems.