Burn areas

Are you using fabric planters? When I used them ONCE, I found that once they filled with roots the water leached through the sides of the planter long before it reached the bottom of the planter., so I wasn't getting nutes to all the roots. I had same spotsmgoing on. Once I doubled the the amount I watered and the nutrients actually made it to the bottom of the planters my new growth stopped showing those spot. I thought what a scam to get people to have to use even more nutes when they already rob us each time we buy them. Never ever used that fabric crap again and never had those problems anymore.

Looks like cal-mag to me as well the plant is near the end of the life cycle so she is using all the nutes left in the leaves 👍🏼 I guess your good and there is no need to worry