Hi, @userhayPYxNJ7z here some tips on setting up face recognition on the Galaxy S20 series, Please follow the steps below.
Please make let me know if this works for you, Thank you!
Just follow the below simple steps to Enable Face Recognition lock on Galaxy S20, S20+, and S20 Ultra:
I see I understand it's a bit annoying when the phone won't open instantly when using face recognition.
Just simple tips, You want to make sure you are not wearing glasses when unlocking the device.
Or if you set up your face recognition wearing glasses make sure you are wearing glasses when you unlock the device.
And also you want to make sure there are no particles interfering in front of your iris scanner.
If the problem does persist, I would recommend a reset factory to the device and check for an update.