FTD doesn’t usually happen in people that young, but it can happen in someone in their twenties or thirties. It occurs more often in people over 40, though (dementias are considered “younger onset” if they start before the age of 65). FTD affects the frontal and/or temporal parts of the brain. The frontal lobe is the same part of the brain affected by ADD/ADHD, so it can have similar effects. For someone with pre-existing ADD, it can just seem like their ADD is getting much worse.

What you described is fairly classic inattentive ADD (not mild!), but ADD doesn’t start suddenly, out of the blue. But, if you are very young, it is highly unlikely to be FTD. There are other things that can affect executive function, though, including depression, so I recommend talking to your doctor about it, and perhaps getting a referral to either a neurologist or a psychiatrist.

PS. I just read your comment about the meds you are on. Some meds can have the impact you describe, on some people. I have had to stop meds that my doctor was trialling on me for pain management, because I felt they made my ADD symptoms a lot worse (including apathy, which is one of the things you describe).