Using a ROKU Ultra 2020 4800X (Firmware says it is a 4800RW. It has latest update), a Charter Spectrum universal remote on a Sony XBR 55X850C 4K TV. The ROKU remote is "Paired", has "One button start" enabled and can control the TV volume.
After using the ROKU player, then changing the TV input to my cable box, any button I push on the universal remote turns on the ROKU player and changes the TV input back to the ROKU player. If I wait 20 -30 minutes after switching the TV input to the cable box and before using the universal remote, The ROKU player seems to be asleep enough to ignore the universal remote. That is a long time!!!
I like and have used that feature for a long time (This is my 4th player).
I apologize if you thought that was the issue.
The problem is that if I use the universal remote before the ROKU player goes into "Deep sleep" (20 - 30 minutes), using the universal remote wakes up the ROKU player which tells the TV to change input.
After the ROKU player has gone into "Deep sleep", you can use the universal remote normally.
Who wants to wait 20 - 30 minutes for that to happen?
That description describes what enabling "1 touch play" does when you push any button on the "ROKU remote". Most of us have multiple remotes. Imagine what would happen if they all turned on your ROKU player!
What I see is two different stages: "Stand-by" and "Off".
When you first quit using the ROKU player (and switch to a different input), the light goes out signaling the ROKU player has gone into "Stand-by". A long, long time (30 minutes?) later it shuts down completely ("Off"). I can then start using my other remote normally???
I just got a Roku Ultra and was having a similar problem with the Charter Spectrum universal remote, except the problem was when I tried to operate the cable box / DVR, that's when Roku would steal the TV's input focus. Haven't yet found a code that solves the problem the way you did, but just physically moving the Roku Ultra box behind the TV and turning it backward so its IR receiver points at the wall behind the TV seems to be preventing any IR signal from the Charter Spectrum remote from triggering the Roku. If anyone else is in the same boat and can't find a code to fix the problem, try physical isolation.