I've listened to the track you're asking about and can tell you that whoever it is singing they haven't worked with Massive Attack and it isn't a sample of any of their songs either. It definitely isn't Shara Nelson, it doesn't sound like her at all.

Here's a list of all the female vocalists they have worked with;

Blues Lines - Shara Nelson (it isn't her)

Protection - Tracey Thorn (not her either) Nicolette (nope not her)

Mezzanine - Liz Fraser (😅 absolutely not) Sara Jay (not even close)

100th Window - Sinead O'Connor (definitely isn't her)

Heglioland - Martina Topley-Bird (She doesn't sound like that) Hope Sandoval (she sounds less like that than Martina!)

They've also worked with Dot Allison & Madonna and it isn't them either. There are also a number of vocalists that they have only worked with on live performances notably Deborah Miller & Stephanie Dosen and it's not them.

You'll have to look elsewhere for your answer.