People who probably don’t know must have placed orders there. Which is why you always use limit orders when trading ETFs.
The risks are the same as any other debt fund. But the in case of Liquid ETFs the risks are very minimal. The reason being they only invest in security called Tri-party Repo which is fully collateralized. They don’t take credit risk, duration calls and hence risks are minimal. The returns will be in line with the RBI repo rate.