If you are seeing a pink screen on your Fire TV 4K device, there is a workaround.
1. Remove power from Fire TV
2. Disconnect Fire TV from CC and connect it directly to an HDMI port on the TV
3. Re-connect power to Fire TV
4. Use the TV remote to switch the TV input to the HDMI input port connected to Fire TV.
5. Using the Fire TV remote, navigate to:
Settings > Display and Sounds > Display
6. Change "Dynamic Range Settings" from "Always HDR" to "Adaptive"
7. Change the resolution setting to "2160p" instead of "Auto up to 4k"
7. Disconnect Fire TV from TV input and connect it back to the Control Center HDMI input
8. Switch TV back to the HDMI input connected to Control Center using TV remote
9. You may get a static/snowy screen when you switch back to the Control Center input. if this happens, unplug the HDMI cable from Control Center's HDMI output and plug it back in.