When you edit the UTMs on any ad in Facebook, this will send your ad back into "review" for a very short period of time. When the ad comes back online, Facebook will sometimes say the ad is in the "learning phase" again, however nothing actually changed about the copy or creative of the ad so Facebook actually is still running the ad exactly the way it was before updating the UTM parameters.
Please note that updating the UTM parameters will reset any social proof on your ad UNLESS you launch a new ad using an "existing post" where the existing post is the original ad with the social proof. For more information about how to launch an ad using an existing post, follow the directions in this article: