Shit sorry ,didnt see the first pics of the thread . Calcium/mag for sure . Calcium creates the spots . And mag ,theyll start turning yellow and dieing rust in sunken patches and leaf stems and plant stem turn purple-ish .
Get some epsom.salts mix 1tsp per liter , and crush eggshells in water for a few days and mix in with your regular watering til it goes away ,but the damaged thick dead part.of leaves will not come back , remove during course of a.few days . And your plant will heal .
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