What could be the reason for high endoscopic lift failure rate?

Hi, many ppl who've had endo. Brow lift show pics where the brows dropped back to the OG position within 2 years. Are there any known factors / predispositions that may cause this for some individuals? I wish results lasted a min. of 10 years. Im thinking of combining brow & cheek. Can they both drop back at ANY time post surgery? Thank you!