The group - winners of The X Factor in 2017 - revealed the news that Rahimtulla, pictured above left, will be absent from the lineup moving forwards as he works on getting better.
"Unfortunately, this video we are about to share with you right now isn't going to be the happy and bubbly sort you usually get," said Jamaal Shurland in a video with bandmates Ashley Fongho and Myles Stephenson.
"But, we feel like it's an issue we should probably talk about because a lot of you have been asking and obviously, even in this video right now, Mustafa's not here.
"He's not been around for the past couple of months and going forward he's not going to be here either.
"But basically, he's been struggling with some mental health issues and he doesn't feel like he's in the right frame of mind to take part in everything we're trying to do right now.
"Obviously, he's our brother and has been for a very long time, so the doors are always going to remain open, and once he feels like he's capable again to step back into the world we currently exist in, then he will be back."
The band released latest single 'Girls Like You' earlier this month and also have plans for a UK tour when coronavirus restrictions lift in 2021. body check tags ::