Tracking

It also may be the age of your Apple ID. See the following from If an app asks to track your activity - Apple Support

In some circumstances, the “Allow Apps to Request to Track” setting is disabled, including: 

• For users with child accounts or under age 18 by birth year, signed in with their Apple ID*
• If your Apple ID is managed by an educational institution or uses a configuration profile that limits tracking
• If your Apple ID was created in the last 3 days

Hello. It looks like this feature is greyed out because your Apple ID does not meet the minimum age requirements. If you are under 18 you cannot make use of this feature.