I am looking for some advice on the yellow spots o...

Very common sign to me personally that i kept soil too wet too long, plus ph became a bit out of range Generally nothing to worry about if you dont repeat it.

It isn't a lighting issue, it looks more like burning from spritzing your plants with water. I usually run both veg and bloom switched on and at 100%, from day one until harvest day and never get any issues with "too much" light, afterall, they are designed to grow in full sunlight, all day, every day. Whatever is the cause, the yellow spots won't affect growth, but running your lights that dimmed, certainly will.

I wouldn't say it was light burn either, on that power with that distance you will probably only get 6-8dli which is just about right if not to weak a strength. Your medium looks quite wet on all your pictures. If you have been spraying a lot and water droplets form on the leaves then they can act as a magnifying effect from the light and burn them bits of the leaf.

That ain’t light burn at 1/4 dim. What soil you using ?