@Leah00 , it would be interesting to do home>settings>system>advanced>factory-reset. But, during the initial setup, tell it you don't have internet. If the problem occurs frequently enough, maybe you could see if it happens in this initial (un-updated) state. Maybe watch antenna tv for awhile, or an HDMI device. (Assuming watching those things leads to the same problem you're having now.).
After awhile, go to home>settings>network to setup your network connection. Then see if the problem resumes (after the tv is updated to the latest update. That might take a day or two. I don't know if does it immediately.).
It would be interesting to see if it's due to being recently updated. If it still happens when when you're un-updated, then it must be a hardware problem. You said it happens on different channels. If you mean antenna channels, then you could stay disconnected from the internet and watch antenna tv (if it's the update that caused the problem.).
(One thing to check before trying the factory reset would be home>settings>system>power. If "fast-start" is enabled there, try disabling it and then do the "restart" in that menu. Sometimes fast-start causes problems, and restart fixes problems (sometimes related, sometimes not). )
You could put your tv on an ordinary timer that would cause it to turn off (unplug) for an hour every night (middle of the night). Those rotary timers that have little push-down segments to have on/off periods.
"People are often amazed at how much we’ve done with the number of engineers we’ve got." (Roku CEO Anthony Wood, Austin Statesman, Oct 4, 2019). "Amazed" is one way of putting it.
