Is there any particular reason that the older batch (on the left) is pretty transparant, and the newest batch is very dark/yellowish?

https://gyazo.com/89caaf559ed05a1e00...57bab8a6b86da5
https://gyazo.com/817c495dfa0ea94be3817acf3286179d
https://gyazo.com/87c3dcc4a6bfe98757f356146dd54d44

Kind regards,

EDIT: Can't seem to insert imgaes for some reason, so I linked to pictures instead of embeding them here.