Must be inserted at the end of the link &fbclid=IwZXh0bgNhZW0CMTAAAR1halReASaJoyMjt6aIVKl5gfCK0cF80SXEdl3z4RBtXcbiX5-dm07ju4E_aem_bxECWnSs3FhYz-BumupLCA
It will be correct like this - https://домен.com/index_69d4d7dd9fd15.php?camp_id=69d4d7dd9fd15&entity_type=private_channel&fbclid=IwZXh0bgNhZW0CMTAAAR1halReASaJoyMjt6aIVKl5gfCK0cF80SXEdl3z4RBtXcbiX5-dm07ju4E_aem_bxECWnSs3FhYz-BumupLCA
Go and make a test subscription.
Pixel Active
fbclid is a special identifier that Meta (Facebook) automatically adds to links in advertisements. It is unique for each user, which allows you to track his actions after clicking on the advertisement. For example, in Telegram, using this value, you can match a subscription or other targeted action with a specific user of the advertising platform. Simply put, this is a unique client code. When testing the Facebook pixel, it is important to set this parameter so that the system can correctly record events and associate them with the traffic source.
In the example, we substitute a random value to check the activation of the Pixel