I have the exact same cable as you (Packapunch Pro Luma Sync) and my PS2/PS3 don’t have that issue. I did have a similar issue before when I played my Jaguar on a CRT, but the colours were fine on the OSSC. Turns out it was outputting TTL sync levels and it needed a capacitor and resistor on the sync line, after I did this, the colours were correct on the CRT and I wasn’t afraid of breaking my OSSC.
I know RGsB is different though and we have the same cables, so it is pretty unusual. I was going to say I have a multimeter there if you want me to test mine, but if it’s just copper wire with nothing along it’s path, then there’s nothing that can be different really.