Why did the market order get executed as a limit order?

The market order might get executed as a limit order due to the Market Price Protection (MPP) (Link) feature enabled by the exchanges. This applies to all instruments in BSE and certain illiquid stocks in NSE. MPP is designed to minimize the risk of orders being executed at prices significantly different from the Last Traded Price (LTP) due to bid-ask spread variations.

On NSE, when a market order is placed for an illiquid stock, it could either be executed as a limit order or rejected based on specific criteria outlined by the exchanges. (Link)

For BSE, a market order is executed as a limit order. The execution takes place at the next best available bid or offer within 3% of the LTP.