I see no signs of Magnesium def.
I DO see signs of flying insect (thrip) damage, heat stress, and possibly Molybdenum deficiency.
You also MAY have an overwatering and/or rootbound problem.
The last pic in the bottom right, that looks like heat stress.

For a better answer,
What are your temps?
How wet is your soil?
What is your soil pH?

And sprinkle some diatomaceous earth on the soil surface ASAP.