There should not be any issue with the number fields in Sitefinity 9.1. I just tested this and I can verify that if you create a custom field of type Number and then from the Decimal places dropdown box select the number of decimal places after the decimal point that can be entered in this field (e.g. 2), Sitefinity will properly save the value entered in this field with the correct number of decimal places after the decimal point.
I am sending attached a short video for your reference to demonstrate the behavior on my side. Can you please let me know if I am missing any steps to reproduce the issue?
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