I see potentially multiple, fairly minor problems. The meta thing that may be going on is that this strain is more sensitive to some things that prior plants were more resistant to for you. In particular, being clones, they came from some different setup than yours, and may be just shocking out a bit. Things to ponder:
- RO water is so mineral deficient that it can leach nitrogen, etc, back out of the plant, I think you may have some of that. I'd give them some light nutes, like 1/4 or 1/8 recommended strength. Having some minor amounts of nutes will be safe. Or you could use tap water, which will likely have some mineral load. People worship RO water, but it can cause some problems.
- A couple of the pics look like overwatering, where the leaves are curling down and under. Are they getting and staying too wet?
- Then the one pic, with the burned top leaves looks like maybe too much light? Perhaps they were rooted under a weaker light (common for cloning), and yours are more than they are used to. Maybe dial the lights back, if they allow that, or raise them a foot until everyone is happy again.
My two cents.