We've had the same issue going on for months and I think I've finally fixed it, so thought I'd post here in case it helps others. I found a separate HDR settings menu that only appears when watching something 4K HDR. For us it was something in Netflix that I had paused. I happened to press the settings button on the remote while there and realised that everything was different. The backlight setting was at 100 instead of 65 that we had it at in the regular settings. I lowered the backlight until the flashing stopped. It got less frequent the lower the backlight number and stopped completely in the low 60s. I'm leaving it at 65 for now and will lower it more if needed. I hope this helps someone else! So glad we don't have to buy a new TV when apart from the flickering this is perfectly fine.