The version of the nRF Connect SDK and its toolchain used for the terminal depends on where you started the terminal from. While the terminal is open, its environment cannot be changed. For this reason, if you copy paste command line invocations of west from the nRF Connect terminal to an external terminal, make sure that both terminals use the same environment. See also Using the correct command line environment in the nRF Connect SDK documentation.
Every time you open a new terminal, the extension verifies and validates the terminal environment, in particular the system PATH and the ZEPHYR_BASE variable. If there are issues, you can find details in the nRF Connect channel in Output in the Panel View.
All changes to the terminal environment are limited to the nRF Connect profile, so the default integrated terminal profile will work as before.
Caution
Do not set Select Default Profile to nRF Connect in Visual Studio Code. If you do, you cannot use many core features of the extension due to Visual Studio Code issue #200558.