Found out the issue which caused the rlmax_w being scaled down.
It was something extremely simple, but still something extremely hard to find.
I had to look all of my modified maps through for several times and still only found the issue by an accident
Every map which can modify rlmax_w and uses fak_uw_b1 (1.52587890625e-5) or fak_uw_b2 (3.0517578125e-5) is affected.
The issue gets amplified if you have multiple corrections (pull-back & IAT) active and you have altered the default values, like I have.
If you disable the corrections at a given point by setting the value to 1.000000 the actual value the ECU will see will be different due WinOls.
fak_uw_b2 for example will be rounded from 0.000030517578125 to 0.000031 automatically. This means that for every correction which gets activated, your actual load will yield 0.9844 correction instead of 1.0.
Setting each cell to be modified to 1.000000 will result in 0.9844 correction, whereas setting them to 1.015808 results in 1.0000 correction.