Broker just sells the number of shares you requested. There is no shares divided in the demat account for long term or short term. You will have to calculate the tax for the long term holding using FIFO rule while doing tax. Zerodha provides the shares which have become long term in holdings.
Yes, another reason to avoid this exercise.
You can try tax harvesting very easily. Calculate the short term profit you gained this year. All brokers provide it. Sell equivalent amount of loss (Nykaa maybe). Buyback after it has been removed from demat account.
Your buy average will reduce and you will save the tax on other short term profit. ( I did the same).
Yes you can save tax on 100000 every year for long term position.
