First time grower leaves dying on my plnat. Pictures included

I was growing my plant for rougly 3 weeks and four days from seed (germination) I did mess up my light cycle a few times and changed it from 24 hrs to 21 and 3 then 20 and 4 which I am still using now. two days ago I noticed some of my bottom leaves going bad. could you tell me whats wrong with my plant or if I am doing something wrong?

As of now you are doing nothing wrong. The initial lower leaves die out naturally. Looks good!

If a few of the bottom leaves dye off like that could be due to improper PH, Sometimes the plant aborts lower leaves that receive less light and focuses energy upwards in the canopy. So far so good id say.