I just going to guess and say that that last pic has symptoms of overwatering. We all find it hard to avoid the temptation to baby our plants, but the truth is that days will go by where you won’t see any progress at all and then one day you are shocked that they seemed to have sprung up three inches taller seemingly overnight.
I personally don’t dome my seedlings and have done fine, but I do maintain a humidity in my tent above 60% during the seedling stage with small humidifiers.
I literally feel like I am underfeeding my seedlings and have learned to get comfortable with it. Until the seedlings pop a 3 leaf node, I never give them more than 2ml of water maybe every other day. It is far better to underwater them. If you do happen to underwater them, then they will tell you. You can then give them a bit of water and they will self-heal within just a few hours. You can’t heal an overwatering situation like that.
It’s far, far better to underwater than it is to overwater. When they first break the soil they really don’t need anything for a few days.