After the macOS update, Tuxera NTFS cancels its NTFS read & write support to the NTFS drive so the iPhone backup work to your Mac process failed. You can uninstall the Tuxera utility and then perform a reinstallation work to get this trouble fixed.
As for the uninstallation work, you're suggested to utilize iBoysoft MagicMenu, which is able to remove the Tuxera NTFS software in one go and clear all the associated files as well.
Then you can go to Tuxera NTFS to download it one more time to proceed with your iPhone backup work.
Alternatively, iBoysoft NTFS for Mac helps you a lot when you want to gain read & write access to an NTFS-formatted external hard drive. Once your free download and install it on your Mac, it mounts your NTFS drives in read & write mode automatically when you connect it to your Mac.