If you leave an app open -- not streaming, just open -- and the Roku goes into screensaver mode, it is possible that the app will either use its own screen saver, or an installed screensaver apart from your standard one. The raining logos is one that I've seen apps use. And that's not a new thing, I've seen that for some time.
Now, not all apps behave this way, but those that do always do it. But, if I'm on my Home Screen, I always get me chosen screensaver kicking in.
All that to say it's the app doing it. Probably after an app update.
Roku Community Streaming Expert
Note: I am not a Roku employee.
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