Hi Abdul Zameer,
DS microflows triggers irrespective of the selection on the Reference selector.
It triggers as soon as you land on the page and when we perform a refresh on the page parameter.
Registration is the page parameter:
Same parameter when include in the Ds microflow, I customize it to execute the logic
Similary, add exclusive split to the DS that is being triggered on the Reference selector.
So main logic will only execute when the parameter exists
Hope it helps!