that works also for me -
I've done both FUBO_USER='[email protected]' and '[email protected]'
and the variables go into the container environment variables appropriately for me.
I am running on docker on Ubuntu so could be how the host interprets the quotes.
Admittedly I'm a network guy and this has become a bit of a hobby for me so may not understand all the nuances of docker (and don't even get me started on my python code - I know enough to have gotten this functional. Sure there are better more efficient ways )