What nutrient deficiency?

Magnesium.

Looks like the need more biobizz bloom bro I’ve had same problem and it’s because I wasn’t giving enough mutes I would still give them 1ml/L of bio grow but it needs more bio bloom try that and see if it makes difference after few days

My thoughts would be ph imbalance. Which could be cause a nitrogen deficiency. I would just double check ph pen is correct makes some fresh water. Make sure not to over water tho. Don't panic it will work itself out. Good luck happy growing

Looks like a combination of a PH issue that is causing CA/MG issues to show up. This is common is first stages of flowering. Check the soil PH or runoff and start going from there.

First thing is to check your runoff ph. if its correct then mu guess would be overfeeding. Do you water between feedings? if you feed every time you can get a buildup. dont try to flush with alot of water as you can wash away the good microbes as well.

I would say she may be overwatered or has slight ph issues.