I recently purchased a house. After moving in , I noticed that the previous owner has connected the floor drain directly to sewer and now sometimes its smell.
Are you sure it doesn't have a S or P bend under there? Since floor drains often only get water down them once in a blue moon there is a possibility there is a trap but it's dried out to the point it lets smells waft back up the pipe.
If it really doesn't have a trap and you aren't interested in installing one yourself the least effort option is to tape over the drain outlet until you get it fixed.
After some digging I saw a pipe but I think its the pipe that takes the toilets waste and connects to sewer line. The floor drains are bit far from where I saw this pipe and digging that much is not possible