light marks

Anybody know what can be causing this ? Just using ph’d water and happy frog soil . There on there 5th week total. Have just showed signs of flowering.

Hi, Would appreciate if a experienced grower would know what it is thats causing the issue prevalent on my plant. One of the pictures with very lights marks was from when plant was 1 week from seedling and I first noticed. Pictures where its more obvious is is 3-4 days from then and 10 days...