In the Twitter for Android, every link you click will be opened in the in-app browser by default.
If you prefer to get the links opened in your default browser instead of the in-app browser, then you need to disable Twitter in-app browser and here are the steps:
That's it. The Twitter in-app browser is disabled successfully, and from now on, the links will be opened in your default browser.
In case, if you prefer to enable Twitter in-app browser, then follow the above steps.