Samsung recently issued a known issue: https://news.samsung.com/global/statement-on-fingerprint-recognition-issue. In summary, there’s reports of a fingerprint recognition issue affecting certain Galaxy devices. If you are concerned about this issue and allow fingerprint for accessing a managed device or company resources, we recommend you change your Android policy to require PIN and let your end users know of this change.
Samsung indicates they will be fixing this issue shortly through a software update. Intune will continue to monitor the situation, including seeing how long it takes for a fix to roll out and evaluate whether we remove the fingerprint support on Samsung S10 devices.
For more information on setting a PIN, check documentation such as this article: