Necrotic holes in plants is an indication of potassium deficiency.
Look at the new growth on your plants to see if it's coming in ok. From what I can see in the picture, it seems to be coming in more normally, however, plants are known to pull nutrients from older leaves to support new ones, so it usually takes several weeks to see if the changes helped.
The old growth won't change. Plant leaves don't heal, and once a bit more new growth has come in, you should probably remove them so they don't start attracting algae (as leaves die, the cell walls loose integrity and release the stored nutrients, feeding algae which will opportunistically grow on the surface).
Do you dose anything besides the root tabs?
All plants need nitrogen, potassium and phosphorus, plus iron and micros, to grow. Some nutrients are dependent on each other, and some are antagonistic, meaning that if the ratios are too out of balance then the plant might not be able to absorb everything it needs, even if some of the nutrients are available.
Your fish probably already provide plenty of nitrogen and phosphorus, but you might want to add potassium if you don't already. If you're already adding potassium, then you are either missing something else (usually iron) or you have way to much of something else (usually phosphorus).
Those root tabs mostly provide micros and a small amount of iron. They have a little potassium, but not much, so the problem will return shortly if not adressed.
I suggest doing a big water change (or several small ones within a few days if you have sensitive fish) to eliminate the likelihood of excessive phosphate, or if you have a test for it you can use that to check if it is elevated. After that, start adding potassium and a bit of iron if you don't already, as the amounts of those two nutrients in the root tabs won't last a very long time compared to the micros. In a couple weeks you should see much better growth. Just make sure to watch out for algae taking advantage of all the fertilizer since it looks like you probably have a lot of slow-growing plants (if the majority of your plants are slow growing, I would halve the dosing of fertilizers from what is recommended on the package).
Sorry for the info-dump. Hope that helps though. There used to be a member on here that was way better at diagnosing and explaining this than I am; haven't seen them on here lately though.
thank you very much for the information. very good information. I actually only use root tabs, I also just purchased
API LEAF ZONE Freshwater Aquarium Plant Fertilizer
API Co2 Booster Freshwater Aquarium Plant Treatment
I am not sure if it would help. I will give it a shot. This is a shrimp tank with Nerite Snails (which I do not think it causes those holes in the plants) I do water change about 30% every 1-2 weeks.
As you mentioned in your post, the new growth might be okay, so far so good, but the new growth has "darker" color in some area, I am not sure what it is.
Again, thank you for the info...
The Leaf Zone should help a lot since it contains the potassium and iron you need.
If you are starting CO2 booster for the first time, start with dosing it at half the recommended amount initially, and after a week or two start increasing until by three to four weeks you are using the full dose. It isn't always a problem, but some species will melt back if you launch straight into using a liquid CO2 supplement at full strength (vallisnaria is particularly prone to this, and I've had cryptocoryne do it too).
Those dark areas might be the start of a melt-back, or they might be damage to the leaf. I suspect they might die back at the dark edge, but you just started adding everything so it could take a little bit for the plants to recover. Patience is the thing with plants.
Remember that if snails have absolutely nothing to eat they may resort to rasping at healthy plant leaves. The older damage doesn't look to me like the work of snails, but they might opportunistically feed on softened weak tissue. If the snails in the tank are pest snails and not pet snails, you might want to try thinning their numbers as a precaution.
Best of luck with getting your plants looking good again.