CO2 can raise the LCP a bit but then the plant is forced to adapt to resource limitation and that is often a costly affair...
Yes, CO2 raises the LCP point, hence why CO2 injected tanks can go by with very little light without experiencing the light limitation problems which are very obvious in a non-co2 tank.
Or is it something visually different?
No different than what folks attribute to low CO2, yellowing leggy growth, no growth, melting/browning, the roots especially can become mush, so symptoms can be differ depending on plants and some last longer, some wither fairly quickly within weeks.
I've posted my own few pictures in a couple of threads, Christos(you
) linked one of them above.
But here are others, most are not mine but the bottom are mine.
Glosso limited on light:
This below shows the same glosso actually in the first phase of light deficiency when it starts growing leggy, then if severe, it goes into the state as in the first picture.
An entire fish tank with limited light, dare to say more than a candle can provide but just about..
The same fish tank after enough light was provided for two months.
Dwarf sag under insufficient light:
Valis under insufficient light(see the tips missing which just kept melting and falling off.....)
Valis under more light in the same tank at the same time:
Same fish tank taken from the same area of the tank:
Light unit working:
Light unit failed and doing by 1/3rd of the light from before:
So, can you see the pattern of distruction? The difference is having plants or not having plants especially in a non-co2 tank where there isn't enough CO2 to compensate for the low light levels.