[radityopradipto]

Hey Jill
as far as I know, polarizer filter doesn't affect your image sharpness at all (meaning very slightly, almost unnoticeable downgrades), if you're buying a reasonably good quality one. Looking at your setting, probably it's about your aperture which too big. F/5 is a bit too big for a landscape shot to ensure everything is sharp from foreground to background.
or by looking at the image, I saw some part of the image, like the foliages, were overexposed.
My recommendation are: try to look at your histogram whether it's overexposed or not, and try shooting at smaller aperture, like F/8-F/13 (meaning you'll need a tripod)
Hope that this will help
Cheers