this is a forced mate, but certainly not in one move

it is a mate in 3 - here is the solution

1. Qxb8+, Qxb8 (or 1..., Kd7  2. c8/Q#)  2. Rxb8+, Kd7  3. c8/Q#

i agree with 1red5a

its a winning game but not a mate...

what how is it checkmate

No... "White to move and lose" is not an appropriate title...

1. cxb8=Q+ Qxb8 2. Qxb8+ Kd7 3. Qd7+ Ke8 4. Rb8#

1. cxb8=Q+ Kd7 2.Qbc7+ Ke8 3. Qb8+ Qxb8 4. Rxb8#

1. cxb8=Q+ Kd7 2. Qbc7+ Ke6 3. Re1+ Kf6( 3. Kf5 Qxf7+ Kg5 4. Rg1 Kh5 Qh7#)    4. Rf1+ Ke6 (Kg6 Qxf7+...#) 5. Qxf7 (wining a rook) ... 6. d7+ Ke5 7. Qbe6#

Althought it was incorrect to name this puzzle mate in one, white is clearly in a winning position.

not mate

this is fake

it hink the title should actually be "White to Move and Lose"

no mate in one

It can't be mate in one when every possible check has a refutation.

How is this mate in 1?  ... Nxd7 not only eliminates the pawn giving check, it gives black a royal fork. Am I missing something obvious?