Exec1 is not AF1
Correction again, Exec1F is POTUS family member but not POTUS
If the president's family members are aboard, but not the president himself, the flight can, at the discretion of the White House staff or Secret Service, use the callsign Executive One Foxtrot.[1] "Foxtrot" is the phonetic alphabet designation for the letter "F", with that being the first letter of "family".[3]
AF1 is any plane with POTUS, but Exec1 is any civilian plane with POTUS (which I looked up along with Exec1F for covvie aircraft with POTUS family member but not POTUS
https:// en.wikipedia.org/wiki/Executive_One
AF1 = any Air Force plane carrying POTUS
Navy1 = any USN aircraft carrying POTUS
Marine1 = any USMC aircraft carrying POTUS
Exec1 = any civvie aircraft carrying POTUS. Add Foxtrot suffix if carrying any family member but not POTUS (@USSS discretion)
So Exec1F could be Ivanka or another family member following AF2 with Pence (and getting .mil escort in the process. Efficient.