If you are an Apple desktop computer user, you still have to upgrade the system as soon as possible.
Apple has just released the stable version of macOS 11.3, which contains some new features and fixes for a large security vulnerability that has been exploited by malicious attackers.
Based on this,
unless you insist on using macOS Catalina for compatibility reasons, it is recommended that you still obtain and install the update through “System Preferences -> Software Update” as soon as possible.
For M1 Mac users, the macOS 11.3 Big Sur update also includes optimizations for running iPhone/iPad applications on the Mac.
The reason why Apple allows everyone to quickly upgrade to the new system
Because it fixes a serious bug that allows malicious attackers to easily bypass the security isolation protection measures on macOS, and even prevents Gatekeeper from popping up warning prompts. If it is used by other malicious software (such as ransomware), the consequences may be more serious.
This security vulnerability has been fixed in macOS 11.3. In addition, Apple has updated XProtect to enable it to detect and warn if any downloaded software is trying to exploit security vulnerabilities in the old version of macOS.