Under "Settings > System > Advanced system Settings > Advanced display settings" some Roku devices have an "Auto-adjust display refresh rate" item.
If this is enabled, the Roku circuitry sends the signal output at the refresh rate (frame rate) used by the original source material, commonly 24 fps (frames per second), 25 fps, 30 fps, 50 fps, or 60 fps. Every time the source frame rate changes, the TV must adjust its display to accommodate the new frame rate, which on many sets results in a short blackout.
This can happen when starting/stopping new programs, and when going in/out of commercial breaks that have a different native frame rate than the programs they are inserted into.
If "Auto-adjust display refresh rate" is set OFF, the Roku converts everything to a frame rate of 60 fps and the TV doesn't have to adjust on the fly.
Roku Community Streaming Expert
I am not a Roku employee, only a user like you. Please, no support questions via private message -- post them publicly to the Community where others may benefit as well.
If this post solves your problem please help others find this answer by clicking "Accept as Solution.".
Streaming Stick 4K+ 3821 | Streaming Stick+ 3810 | TCL Roku TV 43S245/C107X