OpenCart version 4.x is not the most recent, with 4.x released about 3 years ago, it is now fully stable with the majority of the most used modules now available!
Version 4 brings several key upgrades:
Full PHP 8 Compatibility, which means faster performance and better security.
New Admin Design, featuring a cleaner, more modern look for easier navigation
Improved Security, with stronger default protections.
Extension Changes: Offering a New Approach to Modules and Modifications.
These updates can help make your store feel more future-proof and may improve speed and reliability.