What does this "deeplink_no_attribution=true" mean? Should we change it to false for attribution to work?

This flag is used to disable deep link attribution thus allowing us to do normal SAN attribution. SAN partners like Google AdWords/Facebook integration are different from conventional non-SAN partners, where we send conversion data to SAN partners and they will claim the install/events according to their conversion logic and respond to us via API. Branch then analyzes the data from all the partners and attributes the same install/event based on last-touch attribution logic. You will see less data on the Branch dashboard as we show only attributed data for a SAN partner than the respective SAN dashboard.