Why ubuntu doesn't start from the first bash

Apparently WSL starts bash as a login shell. Among other things, this means it reads (in order of preference) your ~/.bash_profile and .profile files. Your subsequently invoked bash command is invoked as an interactive non-login shell and hence ignores those startup files and instead reads your ~/.bashrc (which is presumably where you have done your conda setup).

Regular desktop Ubuntu tries to make non-login and login shells more similar by adding a section to the default ~/.profile that

• checks if the shell is bash (not sh, or zsh, or some other shell)

• if so sources the user's ~/.bashrc file

WSL appears to provide its own minimal ~/.profile that does not do this - but if it bothers you, you could

• backup your current file: cp ~/.profile ~/.profile.bak

• copy the default Ubuntu one from the /etc/skel directory: cp /etc/skel/.profile ~/

or (possibly better), create a ~/.bash_profile if you haven't already got one, and source ~/.bashrc from there.