Sorry I was being abrupt. I was posting from my phone and I hate them mobiles 😛
The light compensation point for plants is increased when you add more CO2 to the tank. So essentially plants that are lacking light can improve if more CO2 is added. The opposite is also true. Therefore the thread you referenced up there is one-sided and omitting vital information.
As I mentioned previously, increasing either the light or CO2 may help. The other option is, look into potassium and make sure you add enough. That's based on the pictures you gave.
And my advise is, observe, make one change at a time and see what helps in a particular situation. There is a lot of generalization going on that doesn't apply in each scenario. I've seen a lot of issues being contributed to lack of CO2 which are definitely not. And a lot of people repeat what they read here or elsewhere previously without trying it out for themselves.
Find one scientific paper that has explored the physical damage shown in plants due to lack of CO2....???? In fact there is none, because as scarce as CO2 is in aquariums, there is enough to prevent the plants from showing physical damage. If you see dying plants, yellowing, chlorosis, etc...its always nutrients and/or light related. Lack or low of CO2 slows the growth considerably. However, if you've got a light deficiency, high CO2 will compensate for that plant wise. Also having lower light and high CO2 will create an environment with less risk of getting algae because algae likes high light.
Hence why in the thread you quoted it is advised to concentrate on CO2 when keeping planted tanks so it does not get messy.. That's for beginners that just follow instructions like robots.... It's just one way of keeping plants but CO2 is not the solution to all issues or the only factor in place. CO2 is a cure for some issues and a growth booster, and also a vital nutrient as all the rest are too. If you lack one of all the factors, plants simply stop growing or grow so slowly that one can't notice....