Some reasons why Comodo should not be used:
1. Comodo is an abandoware (at least since ±2017), containing dangerous old unfixed bugs. And as a matter of principle, an old abandoware software, full of dangerous unfixed bugs, should not be used (neither recommended).
2. Comodo is not an antivirus nor is it an antimalware. Relying on Comodo's antivirus means a 100% chance of infection. And the other modules do not detect virus or malware. Comodo is just a blocker. And like any blocker, directly or indirectly, it depends on the end user. That means 99.99% of users are not able or will never be able to use Comodo.
3. As a blocker, Comodo is not a Security System, it's only a security layer.
4. As a layer, Comodo's automatic blocking mode is based on an obscure database, which classifies files into “known” or “unknown”. This database is not only obscure, but worse, it has already failed in the past, allowing virus and malware to pass through.
5. Windows can be customized to block the same or more settings than Comodo. If Windows does not adopt a blocking configuration, it's for a good wise reason, which confirms that “blocking” is not for most users.
6. Still, if an user wants, he can customize his Windows to block the same or more settings than Comodo. And there are many other software that also allow to block more settings than Comodo. It should be questioned, why to use Comodo, when there are so many other better alternatives to block Windows.
7. If (big if) blocking is a security strategy, Chat GPT confirms that it's better to use LINUX, or don't turn on Windows at all (blocking is like not leaving the house for fear of events, or like transforming a house into a prison without doors or windows). In today's hyper-connected modern times, to continue to think in terms of blocking strategies is to live in the stone age... dinosaurs in extinction.
8. Until ±2014, Comodo had a certain usefulness, because it could block some threats that its competitors could not. But from ±2014 until today, powerful security software emerged, including granular firewalls, with abysmal advantages that way surpassed Comodo. And being free, it's irrational to choose a mere blocker, abandoned, old and full of bugs like Comodo, when the market offers so many other, better and more advanced free alternatives.
9. The whole Comodo software is frozen in time, it was never adapted to modern times, a simple example of this is the Firewall, which still does not allow granular customization of rules for Windows services. If a Windows service (svchost) is unblocked in Comodo, and if that svchost is actually a virus/malware, Comodo will allow that virus/malware to connect to the network.
There are more reasons, but we'll continue later...