Posting this so others can see and samsung can address security issues with this and that users can avoid using this security method. Previously I had a note 9 and the iris scanner was actually very secure.
First of all, not all apps will use or accept the facial recognition security but I have found some important ones such as banking apps will.
Facial recognition on the Note 20 5g and possibly the s20 galaxy has two "modes." In settings, there is a "quick" mode which gives a disclaimer that it may not be accurate. This is on by default, which is not best security practice in the first place. Disabling this takes the camera longer to recognize and the assumption is it is more secure. Well ladies and gentlemen I was able to easily unlock with a full size picture of myself from instagram loaded up on my computer screen. I was able to do this in both quick and not quick modes.
In short, do not use facial recognition on this phone. It is not secure. This is disappointing because the fingerprint works only 70% of the time. Great phone otherwise.
With COVID, IRIS recognition is paramount for using mobile phones and security these days.
They really messed up last two years in design decisions. To be fair they had no way to know China couldn't contain the virus to the rest of the world but could protect reach and every other city in China other than Wuhan. :/
Realy all methods are unsecure to a degree.
Face Recognition: The only company that has any degree of reliability on this is Apple (this is about the only point i will ever give to Apple), as they have a laser grid that actually measures distance. This is very reliable, but is still not 100%. A mugger can beat you up, and then steal your phone, and poit it at your face and presto, it's unlocked. Samsung uses a camera as it's only sensor, which can be tricked, as the original poster mentiond, with a photograph.
Fingerprint scanning: Very reliable, most phone companies have this down, but again, going back to the mugger situation, the mugger can get your phone, and then use your hand to unlock the device. Also both of these can also be used as a method of police getting into your phone as they can command you, legally, to unlock your device with either of the above methods.
Pattern: This method seems reliable, but I cant even say how many peoples pattern I accidentally memorize the first time I see them use it. Secure agains muggers, but not against friends/ family
Pin: These are also easy to accidently pick up by watching, even arrantly, someone unlock their device.
Password: Probably the most secure method here, but also easy to forget, and need to get reset.