For the last few weeks I have noticed a smell coming from my kitchen. Usually it happens when the window is open, but sometimes it appears anyway. The smell is hard to describe, but generally it is unpleasant. I have managed to track it to underneath my kitchen units, specifically a corner away from the sink. For context, I live in a block of flats, 4 stories tall. I am on the top floor.
When looking under the kitchen units, I found pipework in the corner (as shown in the attached picture) and noticed the gaping hole in the wall where it passed through, as well as the hole in the floor for the remainder of the pipework.
My question is a) could this be where the smell is coming from, b) would it more likely be pipework or something else, c) how can I fix this/who do I need to speak to?
Every topic I have tried to research only seems to talk about kitchen sinks, and I can't find anything giving me good advice. Any help on here will be greatly appreciated!