What's wrong with colour capsicum plant

I agree with Sali ji. It's Anthracnose of Pepper Amol Takte . Kindly follow the link

I agree with Sali ji. Apart It's also Iron Deficiency in Pepper . Click on green link for control measures.

Spray mancozeb 2g per liter accompanied by NPK 2grams per liter twice a month

Why leaves are becoming yellow

Wow

First your plant suffer from a severe deficiency on everything but mainly magnesium. So I would say give some NPK fertilizer to you plant that also contain a good amount of magnesium. Scondly your plant will surely infested by Chilli Thrips and maybe also Broad Mite . A pesticide containing Spinosad would be a good choice for a treatment.

rob sir. Thanks for your kind encouragement upvote and e support.

Generally this problem is occurs due to fungus infection and magnesium defeciency . Spray Index 100grm with 200 litre of water. After that you shouldn't apply NPK till one month.

Index and saff spray and change crop

Thank you Safia for your great efforts!