sync hangs and cannot be killed

OS is Debian 12. I copied some data to a usb drive, then ran the sync command to ensure I could remove it safely. The sync command then appeared to be stuck. After waiting for half an hour, I tried attaching strace, which showed no changing output. I cannot kill the sync, even with kill -9. ps shows the sync command in the "D" state. How do I get the sync command to exit without rebooting? What is wrong with sync? Is it just not used anymore? I've never been able to run it before without something like this happening. Can I just leave the sync stuck in "D" for now? Will it interfere with my normal desktop operation? I really do not want to reboot.