I had the exact problem you did. I went around in circles with Roku support until i figured out if I changed screen savers to one of the community ones, this no longer happened. It's something Roku has built into their screen savers as someone else pointed out.
Thanks so much for your response since apparently Roku isn't going to be of any help.
I have not changed screensaver settings in a long time but this issue is only months old. My screensaver had been a digital clock, but noticed that had disappeared and reset to a different one that I assumed was a default. I didn't bother about changing it back and I don't think it would ever have occurred to me to connect the two things. I changed it back and just as you said the problem seems to have disappeared.
I'm surprised or maybe not, that the Roku rep that replied to me, then just ignored me, didn't mention this. Surely Roku knows about this. Perhaps they think by keeping this from us it will make us want to watch their channels. As it turns out, for me at least, it has had the opposite effect.
So thanks again for your help. I had pretty much given up.
You're quite welcome. I shared your frustration with this, believe me. Hard to make the connection between what we were seeing, and the screen saver of all things. I even contacted YouTube because I thought it was their problem, at first. After many hours and some dumb luck I stumbled on this "fix". I even went as far as to send Roku support a video of me recreating this problem and it was 100% repeatable. We still went around in circles after this of them asking me to "try this, try that", but after I found my fix I didn't have any more time to give them.
Maybe this wasn't intentional and deliberate when they coded the screensavers, but at a minimum, they seem to now be embracing filling up our home screens with a bunch of apps we didn't want. Don't get me wrong, I like a lot about my Roku's, but this was enough for me to start shopping around again. I ended up choosing another company for my next devices.
Cheers!