One of the disadvantages of using fast fingerprints in a fingerprint scanner is that it may not be able to detect the difference between different people. For example, when a person touches the scanner with their index finger and then their middle finger, it may not be able to tell them apart.
There are also some other disadvantages of using fast fingerprints in a fingerprint scanner:
One drawback is that they can't be used for identification purposes because they are too similar.
Another disadvantage is that if someone tries to use their fingers on the scanner and then wipes off their prints, it will falsely identify them as present at the time of scanning.