Upgraded to Big Sur, and now screen sharing doesn't work even though I granted app permissions
This screenshot indicates that you have not given any permissions.
In order to grant persmission(s) you have to click on padlock (bottom left, followed by text: "Click the lock to make changes"), unlock (by providing password or fingerprint) and tick apps you want to give permission to. Then you should click on padlock again to lock.
With permissions granted and locked it should look something like that:
