'She is Amanda Seyfried and you cannot fool us', wrote one astonished user.
'Omg you are blessed, I think she’s the most beautiful woman', commented a second user.
Some users were adamant that they had stumbled across the real Amanda while they were scrolling through the app and were baffled to discover it was Rou (left). Right, Seyfried as Sophie in Mamma Mia! Here We Go Again
The clip likening the pair clip quickly went viral on the app, racking up 392.1K views and 3143 comments. Left, Rou in one of her TikTok videos. Right, Seyfried posing for a Lancôme campaign in 2019