Hey there @mozzatron1
Have you tried to ask on Native Instruments support site or forums ? You might find more Traktor users there than here on S.A forums as well as Apple because in the end, it's more a MacOS issue I believe.
So thinking about the MacOS side of things, did you back up your previous MacOS installation before upgrading to Big Sur ? Do you have any way to revert the installation, or a time machine or any other old installation backup where you could access your playlist folder and make a copy.
In case you haven't got an easy way to access a backup, there are some recovery tool option like the free TestDisk from CG Security ( just google it ) but it's cumbersome to use ( all happening in Terminal ) and takes a long time.
Apps like Carbon Copy Cloner allow you to create a bootable image of your MacOS system on another hard drive, even an external drive and that's the most easy way to have a safe backup before performing any upgrade. If you haven't perform such prior backup or don't have any accessible Time Machine backup then I think it's back to tools like Test Disk or finding a way to revert the MacOS upgrade.
Last thought here, are you sure your folder is not simply hidden, or maybe permissions have changed, or it could also be that Traktor is simply not working well on Big Sur and that the app does no longer see your folder.
Definitely investigate with both NI & Apple support IMO and in last resort some recovery tools like Test Disk.
Hope this helps