I have Broccoli and Bok Choy seedlings under sunlight for 2 weeks but looks like the stems are thin and leggy? They are about 5cm tall.
not too badly but they are stretching for the sunlight. move them to a brighter window or even to a porch where they are a bit sheltered from direct sun and a lot of wind. you don't want to dry them out and kill them. those look like broc or cabbage and can take cooler weather.
Just curious, what soil mix did you use? I ask because sometimes this can happen, if the soil is depleted with certain minerals - Like iron for example... Leaves also will become yellowish, (if depleted soil is used).
I think they are under direct sunlight about 5 hours a day...too much? Now I moved them to a place that may get reduced to 2 hours a day.
Yes, I think your soil might be depleted. But not to worry, as you can revive it. There are many ways, the quickest, easiest, and safest way is to introduce a natural fertilizer, (not synthetic) - You can do it even now, and your seedlings will instantly recover.
Mine look about the same as yours. I started them in peat pellets and transferred them into a good soil mix in medium size pots. I figure they will survive or I buy plants from the Garden supply.