When I enabled line numbers in all editors by following this
link, indentation in python disturbed.
Whenever I write a new function, earlier editor used to properly indent the tab with the function definition name but when I enabled line numbers, indentation stopped working.
When I write declaration, def fun():, and hit enter, cursor starts from the 0th position rather than function name's indent. I was able to reproduce this issue on another computer too.
I removed python tools and reinstalled and indentation started working fine again. [Restarting VS also fixed the issue.]