East scored a huge chart smash in 2015 with ‘Sax’, the year after she finished second on the ITV show.
Although it missed the Top 10, her debut album Love, Sax And Flashbacks went on to be certified Silver in the UK.
Now, after nearly two years without any new music being released, she has left the Syco roster.
“Fleur had some great times with Syco but it was felt by both sides now was the time to go down different paths,” a source told MailOnline.
“She will always remain a friend of the label – because everyone’s really fond of her.
“FLEUR EAST DESERVES SO MUCH MORE,” raged one person on Twitter.
Another wrote: “Gutted that Fleur East has been dropped, she was wasted by Syco – Love, Sax & Flashbacks is one of the best #XFactor albums ever.”
“In other news of black women getting mugged off, Fleur East has been dropped which I can’t say surprises me but what a fucking waste,” said a third.
“So the most criminally underrated pop star of our generation, Fleur East, has been dropped by SyCo. I hope she can do better now tbh,” wrote yet another Twitter user.
East is still thought to be planning on releasing music: she tweeted at the start of this month that she was “back at it”, alongside a photo of herself in the recording studio.
The only X Factor acts still with Syco are James Arthur, 5 After Midnight, Ella Henderson, Louisa Johnson, Little Mix and Louis Tomlinson.
Fifth Harmony, formed on X Factor USA, are also on their list, as is their former member Camila Cabello.