In iOS 14.5 Apple introduced a privacy prompt where users need to give permission first before they can be tracked. This is a requirement for all apps that track your activity across your iPhone, iPad or Apple TV. As Matomo does not track behaviour across apps or phones, this privacy prompt is not needed when using Matomo. If you have multiple apps and you are using Matomo’s User ID feature, then this should also not apply to you because you are only tracking a user in your own apps.
You can read more about this on Apple’s User Privacy and Data Use page.