Have you tried SotC remake? It's not as in your face as in other titles yet it greatly enhances the game. Tetris Effect is lovely in HDR yet only 1080p.
I have all the settings enabled on tv and pro but I rather run without the breakout box anyway. It must be adding some display lag if it's touching the signal. I rather directly connect to the tv and use ARC for sound to keep display lag to a minimum. The random blackouts happened without the breakout box and stopped after switching the ps4 pro to HDCP 1.4. It wasn't frequent, most days not at all, yet when you are in the middle of an online race and the screen blacks out for 1 second in a corner, not good.
I was going to try SoTC but I seen TLG already in my library so I'm DL'ing that, Detroit and GT sport. I did try tetris effect and it's quite cool in the menus but the effects are fairly unimpressive outside of VR.
Did you turn HDR on in the menu? I think it looks quite lovely. I actually prefer it on my 4K HDR tv than in PSVR.
I should play TLG again, played that before I had the 4K HDR tv. Thanks for reminding me of that one :)
GTS is still the best though. Every time I play that it still wows me.