Ah ok, so definitely enough and all slots filled :)

Any benchmark I have seen for the i9-13900k showed good improvements up to 3200MHz (CL16) but only little beyond that. The fastest DDR5 RAM in games is usually <10% faster than mediocre DDR4 RAM.

Regarding Tarkov I saw in detail tests with other CPUs where RAM speed did not really matter - well beyond 3200, there is a Reddit post from someone increasing it from 2133 which helped him a lot (in line with what I saw and wrote before).

3200MHz CL16 is exactly the line where you should be fine. I assume you have 2x8GB, right? Which game did you notice an improvment when pushing to 3600MHz? You may also gain/lose a few percent if you put them in the correct/wrong slots - look in your mainboard manual if you are unsure.

Yeah I agree with the minimum fps and maximum frametimes. 33.3% higher (I assume average) fps because of 12.5% faster RAM sounds implausible.