OK, so I just did a multi-update (probably a bad idea):
DAZ Studio from 4.10 to 4.11
Octane Plugin from 18.104.22.168 to 22.214.171.124
And NVIDIA drivers from 417.71 to 430.86
Before the update everything worked just fine.
Now all seems to work fine, except for the face material of the RedSpec face material for the Victoria 4 character - which now looks like the image attached (PMC kernel used (not using any other)).
Not sure what causes it. However, it breaks all my saved scenes and face material presets based on this material.
If I use the V4 character that is using surfaces that are based on the material mixes from RedSpec G8 then all is fine.
Any clue what can be causing the problem?