You're lumping "not sure" in with "oppose the ban". You could just as easily lump "not sure" with "support the ban" and conclude that not banning it is deeply unpopular.
If you're trying to argue that a majority favors banning it, then, obviously, all opinions other than "favor banning it" have to be lumped together as "don't favor banning it"
Here's the actual poll: https://www.pewresearch.org/short-reads/2024/09/05/support-f...