@owen-t
It’s still possible to modify the « Sea surface temperature » layer colors. This can be done by « Temperature » setting in the list. But this setting alters « Air temperature » and « Sea temperature » in the same way, which is not very practical.
The « Air temperature » scale should cover a range of -70°C to 50°C, while the « Sea temperature » scale should cover only a range of about -2°C to 33°C. So, with a specific color setting of the « Sea temperature », this would give a much more detailed scale of the « Sea temperature ».