I own three roku sticks and and subscribe to Fubo TV .. all 3 TV's I have bandwidth saver turned "off".
I am happy to say that on 2 of the 3 TV's, I can go back the next day, turn on the TV and and the same streaming app is still going. One of the TV's does not.
What else can be causing that?
That's what I thought. And if you just press a key to exit the screens saver, it goes back to wherever you were before (presumably Fubo)?
On that unit, go to Settings > Theme > Screensaver wait time > Disable screensaver.
You didn't answer this: "And if you just press a key to exit the screens saver, it goes back to wherever you were before (presumably Fubo)?"
From your subsequent post, I assume it exited the screensaver to Home screen rather than Fubo.
I don't have Fubo. Is there some setting in Fubo that controls timeout/screen saver/idle time, or something similar? If so, possibly it is specific to that installation, not your entire Fubo account.