Hi... Is this calcium deficiency and it is too lat...

yo creería que es una deficiencia de calmag, pero sinceramente nunca tuve una deficiencia de magnesano, en todo caso si @growinggrannie está en lo correcto, añadir calmag a tu riego no hará nada malo, la toxicidad por calmag dicen que no es muy frecuente que suceda. sin duda la agregaría para ver como evoluciona sea lo que sea que decidas hacer

It's all said below...

I'd be willing to bet it's a manganese deficiency, not calcium... you've got to get a handle on the ph! Have you checked the ph of your runoff? If you don't have a PH pen, invest in one... it (for me) has been THE most essential tool for good grows! What you need to do right now is to flush your plant. That means, since you're growing in a 3 gallon pot, you need to run 9 gallons of PH'd water through her and then let her dry out. When she's dry, you can start your nutes again but at about 1/2 strength. Since she's in flower, you also need to SLOWLY get rid of those bad leaves... don't do it all at once because that would most likely be too stressful - but you want to get rid of them because you don't want to invite other pathogens into your grow, they're not doing the plant any good and I swear plants LIKE to "look pretty" ... This is a good article on manganese deficiency and what to do about it... https://www.royalqueenseeds.com/blog-manganese-deficiency-in-cannabis-plants-n577 but my STRONGEST advice is to invest in a PH pen and make sure whatever you're giving your lady (water or feed) that the PH sits between 6.0 and 6.5 with 6.3 being the "sweet spot"... since you're dealing with what I think is a manganese deficiency, you need to make sure the PH sits at 6.0 ... Good luck! She'll recover and be just fine!