Why are the market orders blocked for some ETFs during the first two minutes of market opening?

Due to a temporary lack of liquidity, market and Stoploss Market (SL-M) orders are restricted during the initial two minutes of the market opening, specifically from 9:15 AM to 9:17 AM, for the following ETFs (DOC). Additionally, Market and SL-M After Market Orders (AMO) will be temporarily blocked for these ETFs during this period.

If a market or SL-M order is submitted for an ETF between 9:15 AM and 9:17 AM or if an AMO for ETFs is placed during this time frame, you will encounter the following error message: