If it's how you've set up your browser, MetaMask Extension is automatically updated when a new version is released.
While most browsers encourage users to get updates automatically (as do we), users can enable or disable auto-updates on some browsers.
Chrome-based browsers (Chrome, Brave)
Google Chrome and similar browsers, such as Brave, don’t (explicitly) support users to disable extension auto-updates. Some users explore workarounds here, but they're complex and we would not encourage our users to explore this route.
- In the search bar, type: 'about:addons'
- Click on the MetaMask extension tile
- Scroll down to the 'Allow automatic updates' field and adjust according to your preference.