You can see if it has something to do with running from receiver, by connecting the Roku device directly into the TV via HDMI and see if issue resolves itself. (helps isolate if device issue vs a possible switch issue)
Would also try disabling the Power Savings feature of the Ultra 4800 and see if that setting may be a culprit. (Settings/System/Power/Auto Power Savings/20-min inactivity [uncheck to Disable]
I have tried it with the Power Saving On and Off - same results.
It might be related to being connected to the receiver, however it started to make this noise immediately after a software update (Oct 2022). And is fixed by powering off and on the Roku (receiver is left on during the Roku reboot).
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