title: Something weird is happening with the GA4 parameter 'coupon'
body: <p>I have a table in which I have the number of times that a coupon has been used. I wanted to add the dimension source/medium (to know where my traffic is coming from), and the total changes a lot. Wonder what could be going on here?</p>
  <p><a href="https://i.stack.imgur.com/McEIU.png" rel="nofollow noreferrer">screenshot 1, inicial table</a>
  <a href="https://i.stack.imgur.com/UYM6a.png" rel="nofollow noreferrer">screenshot 2, second table with source/medium</a></p>
  <p>*edit: I tried with another parameters of the purchase event and its happening the same</p>