My plants are only going on 2 weeks

Once in a while there will be runts. I would throw it away and use time and love on more productive plants.

After 2 weeks in that tiny amount of soil, they will need transplanting ASAP! There would be hardly any room for root growth and this will stunt your plants severely and is probably why the smallest one has stopped growing. Transplanting ASAP is the only way to help these plants. Starting seeds in cups this small, even if filled to the top, which they should be, will never give them the best start in life. Use containers at least twice as big and the seedlings will grow much faster and healthier. When transplanting them, you could bury them as deep as the cotyledons, (the little rounded leaves) and in time roots will sprout from the buried portion. Hope this helps,............ Organoman.

Add more soil to the cups as they stretch . Giving more room for roots. Then repot soon. 👍

Move your light a little closer so they wont stretch any more, also fill the rest of the cups with soil and that part of the plant will produce more roots. When you transplant bury the plants all the way to the first set of leaves. Hope this helps good luck!

It will be fine, sometimes you can just get a runt, no biggie though, I've found that the runt can grow bigger than the normal plants sometimes.

No reason why it shouldn’t be okay just repot it soonest and hope for the best