An oldie but goody.
Part of the .tiff is a barcode.
Ouch... Well, we do not know about the final resolution of the file, the color mode of the barcode but there are potential problems here.
The Bar Code has been scaled up.
Dam. The potential problems are not potential anymore! They are here.
Depending on the real size of the barcode part, it can work or it is totally useless.
Using a TIF file implies that you are doing (or they did) the layout on the wrong program.
Let's assume the resolution is decent (we would need to analyze the number of bars, the type of code, the total pixels of the section and see how many pixels are making each bar and white space, besides checking the lineature of the output file)
Option 1
Convert the RGB file to CMYK.
Make a selection of the barcode and simply play with the curves or levels. Eliminate any CMY trace and darken the barcode in the K channel.
Option 2
Cut the barcode.
On the layout program simply paste a grayscale version of the image, with some adjustings in the levels. The same as option 1 but with only the grayscale channel.
Option 3... The correct one
Make the barcode again and use a layout program to insert it as vectors.
Making a barcode 100% K implies two things.
A. is made of only one ink (not necessary black)
B. It is not screened.
Here is an image of what do I mean by screening.

If the barcode is big enough this screening will have little effect on how well it is scanned...
But I really doubt you want a barcode really big... so make in vectors.