AF55 turned back to IAD?

Air France 55, IAD to CDG, turned back to IAD after about three hours flying, somewhere near Newfoundland. Just landed (although oddly Flightaware is reporting that it landed early at CDG. Huh? It was able to maintain altitude the whole way back, but at reduced speed. I’d guessed engine failure, but perhaps an issue requiring reduced throttle? Any reports on what happened?

We’re showing it landed at IAD
https://flightaware.com/live/flight/AFR55/history/20210528/2225Z/KIAD/KIAD

Yup; wondering what happened, but safe return, at least.