I've been doing testing on mine for the last few days and have some results. It would be great if someone else who has the same problem could run the same tests and see if they can replicate my results.
Not sure if this did anything but I did a factory reset and am running V026 Firmware. Not using HDR and have a user colour profile with Uniform Brightness on and Brightness set to 100.
Test 1 - Screen left on standby while PC is off. Turn PC on and after exactly 4 hours of use it forces pixel refresh. Screen needs to be turned off with the remote after being unresponsive for 6 mins then back on again.
Test 2 - Screen left on standby while PC is off. Turn PC on, but before using it for anything, go into menu and force pixel refresh. Come back after the 6 mins and the screen is back on. Screen does not trigger forced refresh after 4 hours from doing this. I ran the screen all night, after 8 hours I received the notification to run pixel refresh, but it did not force it to happen for 10+ hours of use.
Test 3 - Screen off overnight using the remote rather than on standby. Turned PC on and have been using it for 5 and a half hours at this point with no forced pixel refresh cycle and no message. I'll be using it for another 8 hours roughly tonight so I will report back with any changes.
But... I think it might just be a matter of turning it off rather than leaving it on standby. If anyone else can check theirs, that would be great.