Well, I'm not trying to take a jab at your age or anything, but based on your profile pic, I'm assuming you're advanced in age a bit. I've actually read some research that says as you age, your fingerprints become less well defined. They essentially aren't as deep as they used to be. And that can have an impact on how well the fingerprint scanner picks them up to begin with. Just sayin, it might be less about the phone and more about the depth of the ridges of your fingerprints. Maybe try a different finger? Or scan several of them? Just a thought.
My mom is in her early 70s and has been struggling with the fingerprint scanner picking up as well. I think most of the time she just uses her pin to unlock it. My fingerprint still works on her phone tho

What?? I bought and programmed it for her... lol...