Hi
517b693351a2 ("Bluetooth: btusb: Always fallback to alt 1 for WBS") was applied to mainline fixing (restoring) behaviour to pre 5.7. As the commit message describes in effect, WBS was broken for all USB-BT adapters that do not support alt 6.
Can you consider it to apply it to back to 5.10.y?
Regards, Salvatore