Many, if not most, minimalist printers are manufactured to keep material cost low for competitive pricing and so do not have any more costly provision to be silent in operation. Fan noise tends to be loud and since it is intermittent perception makes it seem even more so.
Schedule Hack: Rather than working to make an inexpensive machine quiet, which could compromise its proper operation, consider operating the unit when noise is least objectionable such as daytime, during business hours, say.
Mealtimes are normally noisy for the average person so few would notice your addition to the urban din.
Organize your printing so that you get everything done at one convenient time, all things considered.
Chances are what you need to print is not so urgent that a slight delay would have dire consequences.