A month ago, I would have been posting a "me too" on this topic". But I found a solution that works.
The remotes that come with the newer Rokus use radio waves to communicate with their Roku player. And those radio waves are vulnerable to interference from other electronic devices. Especially other brands of radio-remotes. The source of interference does not even have to be inside your house. My hypothesis is that radio interference can be seen as button presses by the player.
The solution that worked for me was to unpair the included radio-remote from my Roku Ultra, and switch to a "simple IR (infrared)" remote. To unpair the remote, I needed to do a factory reset on the Roku with the batteries removed from the remote. And then go through the reset process using the simple-IR remote. The player responds to simple-IR remotes without any pairing required.
For me, no more ghost button pushing.
Of course, simple-IR remotes can not do voice commands. And I do not know how well this would work for stick models behind the tv, Unless you had an extender cable and could position the stick in front of the tv.
