Magnesium problem?

Wondering if im having a magnesium deficiency. If so calmag+ in my next feeding? Also in first week of flower.

You should provide more info.

Lighting, nutes, strain, medium etc.

300 watt led grow light. Fox farm ocean soil. Mango kush indica. Only been giving light fox farm big bloom after 4 weeks only soil fed.

Top of plant seems ok. Issue mostly at lower leaves

Better pic of issue