Cracked versions are often modified by third parties. This can lead to silent data corruption, meaning your backups might look successful but fail completely when you actually need to restore them.
A search on GitHub for "Veeam Backup and Replication 12 license key crack" or related terms yields several results, including repositories and gists that claim to offer cracked license keys or bypass mechanisms. However, these repositories and gists often pose security risks, as they may contain malware, backdoors, or other malicious code. Cracked versions are often modified by third parties