I never had much luck cloning in rockwool with a dome. Every time I would get mould as I could only attend to them once a day and the dome had no breather holes.
Just a couple of suggestions
Firstly looks like you have the remnants of previous grows in your tray or at least residual salts in the bottom, this might suggest less than a clean environment. It needs to be as clean as possible, the environment you need for clones is perfect for fungus and moulds to flourish so always bleach clean between attempts.
I find if the leaves touch anything they will start to look like yours. Other clones, the bottom or sides of the trays or anything else they can touch allows moisture built up and the leaves start dying.
You have too much light IMHO. Unless they already have roots then limit the light they have. I use only two 4 tubes during cloning this does 30 clones in a small area, just enough light to let them know where it is, not enough to grow from. You want to promote root growth only.
I notice you have a couple being supported dont use skewer sticks
ever
I lost 40 clones once to a weird black spotty fungus which grew from the skewer sticks I used to support the clones. It grew within a day and was impossible to get rid of. Use something thats not porous, nothing wooden, bamboo or fibrous you dont know where that has been or what nasties they can have in them.
It is very easy to burn clones if you foliar feed with nutes or additives. They shouldnt need anything until they have roots besides lots of moisture.
It is very dry in there, you need to keep some water in the bottom of the tray, not much just enough to keep the humidity up and stop the area drying out. - If you use a heat mat then you need water in the bottom of the tray or it will get too hot - make sure the heat mat isn't too hot or you will slowly cook the clones.
Try mild H2O2, Phd low ppm water to hydrate with. The H2O2 really helps stave off nasties and ensures O2 is available for the roots when it they come through.
Use your nose, if it smells musty or old then more fresh air is needed under the dome. You can smell mould before you can see it.
I have a bunch of deformed clones which I saved recently, looked worse than yours and had signs of mould. They are 3 tall now and look like there was never a problem. The leaves you have now will not recover but new growth will take over after the roots come on, just keep them going till the roots come through then youll be fine.
