I normally run my blades into the ground, and finally changed mine out after it was like running a butter knife over the fabric.
I have a FISKARS 60mm contour handle, that I've had for a few years.
The replacement blade was "name brand" but I can't remember what it was.
The packaging did not look tampered with or damaged in any way.
Now, when I changed out blades it seems like the new blade has a wee smaller diameter. Where I used to be able to cut through several layers of fabric, now I can only do one. More than one (doubled over) piece of fabric, I need to press my thumb on the button to click out the blade to give it a little more OOMPH.
Has this happened to anyone? Other than having a dull blade, it was working fine before the switch. And of course, I used the packaging to seal the old blade in and throw it away for safety, otherwise I'd have more info!