Occasionally, Windows Defender or other antivirus software might flag a new update of MultiMC as "unknown" because it isn't digitally signed with an expensive corporate certificate. This is common for many open-source projects.
It’s been around for years and is widely recommended in modding communities (including FTB, CurseForge, and Technic fans). If it were unsafe, the Minecraft community would have flagged it long ago. is multi mc safe
Some antivirus software might flag Multi MC because it injects Java code into a running process (common for game launchers). That doesn’t mean it’s malware—just that AVs are cautious. You can check VirusTotal or community forums if you’re worried. is multi mc safe