So, some of their internal emails were leaked. Some of their emails were breached by the same attackers responsible for the SolarWinds hack. It's worth mentioning that Malwarebytes were recently affected by a cyberattack. Not to mention, the free version only has malware scans, and other features are locked behind a firewall.
That said, it doesn't have an integrated firewall. Their advanced virus detection techniques and several security features protect against a garden variety of online threats. Malwarebytes is a safe antivirus service. Visit Malwarebytes to learn more about the features Is Malwarebytes safe? The free version has no real-time protection.