I'm using 40% ocean forest, 40% happy frog, 1...

Have you dimmed the light at least 50%. If not, its definitly light burn. You have a very bright light and 100% at 24 inch is just too much for your young plants. I usually have my TSL at 30-40% and 24 inch at this stage. So, if you havent, dimm the light more than 50%. After that, new grow should look fine. During the grow, slowely increase the power of the light.

Type variegation in Google to see more issue like this one , it's not harmfull for the plants and cannot be cured

Hey :-) we should know how high fine Ec is, otherwise it is difficult to say anything

Here I think it's more of a case of something like this rather then Tobacco Mosaic Virus... https://www.lamota.org/en/blog/five-genetic-abnormalities-affect-cannabis-leaves/

Hi! Could be genetics related too but to me that looks like a tobacco mosaic virus. I don't think there is any cure for that BUT from my understanding it is purely cosmetic thing. You can see how the leafs "Curl" to the side that is yellowing. https://www.growweedeasy.com/cannabis-plant-problems/tobacco-mosaic-virus-tmv look at this and you notice the similarity.