MTM settlement of sold option in hedged option strategy

I am new to option selling. But I am sure many of you maybe having this doubt.

I noticed that for the calculation of margins, brokers (even zerodha) consider only the sold option and not the bought option.
For example let’s say that my max profit and max loss are capped to 4k and 10k respectively. And a margin of 30k is blocked for this position. But if later the position goes against me then addition margin is asked maybe 45-50k now.

Why is it so?
As I have hedged my position and I can’t lose more than 10k. Why so much of margin is asked?
Is there any way to fix this? As it reduces ROI.
Is there any broker who consider bought option for MTM settlement?