Public Burn Function may allow anyone to call burn function and burn tokens in a contract. It can be dangerous. There has been many instance in past where contracts had public burn functions and they were exploited well.
It can be prevented by implementing correct access controls like onlyOwner or by making the function internal with correct access control logic.
https://medium.com/quillhash/shadowfi-301k-burn-function-exploit-analysis-quillaudits-45a17ce04193