What is wrong with my plants

hello guys
So i have 2 plants and they are 18 days old
,Moved them to larger pot 6 days ago ,give them only water, light 22/2

But i can see all the lower leaves are getting sick and they both having the same problem. It started 8 days ago and slowly spreading


This is my second grow and im doing every thing exactly like i did it in first grow exept that in my first grow my plant was 100% healthy.

Thank you

The pic is a bit blurry, the new growth looks good, If the new growth continues to remain healthy just carry on, it was likely because seedlings are sensitive and can quickly show damage then rebound on there own. If the problem begins to show in the new growth that looks good now then you could have a problem. Good Luck!