It seems they have made a breaking change in 6.4+
Library\PackageCache\com.cysharp.unitask@e602fc8de550\Editor\UniTaskTrackerTreeView.cs(58,43): error CS0619: 'TreeView' is obsolete: 'TreeView is now deprecated. You can likely now use TreeView instead and not think more about it. But if you were using that identifier to store InstanceID data, you should instead opt to upgrade your TreeViews to use TreeView to get the proper typing.'
It seems they have made a breaking change in 6.4+
Library\PackageCache\com.cysharp.unitask@e602fc8de550\Editor\UniTaskTrackerTreeView.cs(58,43): error CS0619: 'TreeView' is obsolete: 'TreeView is now deprecated. You can likely now use TreeView instead and not think more about it. But if you were using that identifier to store InstanceID data, you should instead opt to upgrade your TreeViews to use TreeView to get the proper typing.'