Please please please please please don’t use third-party apps to dispute info in your credit file.
When you’re looking at Credit Karma and its ilk you are not looking at your full credit report. You’re looking at portions of it sent by the bureaus in raw data format to CK, who then maps a subset of what they receive into their GUI.
For something as important as a credit bureau dispute, you don’t want to use a third party’s partial interpretation of what’s reporting.
Secondarily, CK only shows you interpreted portions of two of your four files. It doesn’t even show you parts of what’s on the other two.
Plenty of people will post anecdotes of how this worked just fine for them. You need to be concerned about how difficult it gets to fix something when the first half-assed attempt fails.