Ps to the original poster. I screw things like this up in my 2nd language all the time.

"more" and "-er" are sort of redundant. You could say

More light (but this is just awkward - you'd just say lighter).

Much lighter gives an extra degree of lightness than lighter.

Much much lighter even moreso. There's nothing wrong with saying it like this in an informal context like this, but it would generally be better to use words like significantly, vastly, enormously, slightly, a bit, considerably etc to modify the degree of "lighter"

Any LLM could explain the nuances of all of this in much much more detail (this actually makes sense, because detail is not -er).

English is difficult, but dont let that stop you - it is easy to communicate effectively with even a low degree of proficiency, when the other person is acting in good faith.