Similar problem: Both Phone link apps (Windows 11 and Android on Samsung S20) doesn't allow to switch audio to computer. In Windows call is showed in a new window but switch buttons in disabled, in the other hand call in the phone shows connected to computer but switch automatically to phone even when I do manually it keeps switching to phone. Call audio keeps taking place in phone. This functionality worked fine some months ago when I was using same phone and another Windows 10 computer.
I tried all possible solutions I found on the internet including reinstalling apps, unpairing, disabling audio enhancement, allowing all permissions in the phone. All is working fine with my apps in the computer excluding Phone link.
Hope Phone link app team fix this error.