Why do Google Ads get Disapproved for destination mismatch

Google has a destination mismatch policy, which indicates that the final url should not have any redirect when a user click on a Google ad. You can refer to a Google doc here: https://support.google.com/adspolicy/answer/6368661?hl=en

While Branch links will always redirect user before taking them to the destination, they get disapproved if used in the final URL section of their ads, hence it is recommended to use the Branch link in the tracking template URL instead which allows for parallel tracking and does not break attribution for web based campaigns.

More on parallel tracking and general FAQ related to Google ads can be found here: https://help.branch.io/using-branch/docs/google-ads-overview#general-faqs