Why don’t you use your AVR?
If you have your TV connected through ARC means it’s 2 way traffic.
Just looked at specs of your AVR and it had hdmi 2.0 support.
I run a LG 4K TV to a Denon AVR and on these inputs are my PS PRO, and my Kodi box.
When I switch to movies on kodi, my AVR goes to the mediaplayer input, the audio is set to whatever passthrough the movie has, and every setting is possible, and sends the 4K (HDR) signal to tv. Same with my PS Pro.
Just activate HDR on your tv on the hdmi port that runs to your AVR and when possible, set your AVR settings to HdMI advanced. This os only when you have HDR compatible stuff.
Your AVR is you hdmi hub/switch
How do you have this all set up?
I have a 65" LG C7 OLED and a Denon x2400h and have no end of issues with HDMI-CEC, I'm considering turning it all off completely.
Every time I switch my AVR or TV, or switch back to HDMI 2 on the TV on it switches the AVR to the Kodi player input. If I disable CEC on the Kodi player then it always switches to my Chromecast. I have everything connected to the AVR and then to my TV on HDMI2 with ARC turned on. I have no audio issues, just lots of auto switching issues.
It's annoying because if I use my phone to start playing from my chromecast the TV and AVR automatically turn on, but then after a few seconds it switches to the Kodi box.