IMPORTANT UPDATE:
I have remembered that there is one more setting that could have effect on this. In the settings, there is HDMI ULTRA HD setting for each HDMI port, which you can set between Standard, Optimal and Optimal (automatic game setting). I had it on the last one, Optimal (Automatic Game setting), which enables VRR and ALLM.
So I have tested the Optimal setting and voila, majority of the flickering is now gone even when the Light Boost is at the Maximum setting. So it seems that the issue lies elsewhere. It's still worth pursuing this issue in my opinion, but considering the VRR is not the best in these TV's anyway, I will have to live without it.
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Philips OLED TV's are great for the money, I own one myself, but there is one major issue that I see with them. Underneath the picture settings, there is one called "Light Boost", which is essentially dynamic contrast/brightness combo. There are multiple values you can set it to, starting from OFF, to Minimum, Medium and Maximum settings.
Setting it to OFF results in a VERY dark picture even in a pitch black room, all the content, games or movies will have a lots of details lost in the darkness and it's very hard to watch anything, or play anything under the OFF settings.
The Minimum settings lightens up the screen significantly and personally would be my go to setting for watching SDR content. When watching or playing HDR content, the Maximum setting should be always selected, so you do not rob yourself from the peak brightness this TV can do.
HOWEVER, this settings except for the OFF one has one major flaw, as in reality, it's not really a static setting of brightness and contrast, each of these are a dynamic setting where the TV will try to calculate and apply brightness and contrast depending on what is happening on the screen. While it's not that much of a problem when watching movies usually, when playing games and especially in HDR, under certain conditions the brightness will start to rapidly fluctuate and the screen will flicker for a short time, which can be very distracting and annoying.
I have found one way to easily reproduce this issue if anyone have one of these TV's and want to test it out, the easiest way is to start up God of War in HDR, equip the Blades, preferably go into some darker area and start mashing the R1 combo. At the end of the combo when Kratos moves blades in a X pattern across the screen, the TV brightness will flicker for a second like crazy. It does it in all 3 dynamic settings (minimum, medium, maximum) where it is the worst on the maximum one. When you have it at OFF, it does not happen at all.
I have created a video where this issue can be seen: https://youtu.be/a5XaNMlSckM
From my point of view this is a major flaw where Philips do not let us set this as a static value and only implemented this dynamically. This could be solved via firmware update and have such static setting available.
