I am blessed that my home shack is in the basement.
But, I had a major reduction in noise when I grounded all of my equipment together with short pieces of coax braid I had salvaged and made into straps. These were connected by hose clamps to a copper pipe that runs the length of the radio table. Then earth ground is connected to the pipe. This is all in the ARRL Operators Manual.
Also, vertical antennas are inherently noisy, because a lot of noise is vertically polarized, such as lightning.
You might do a little Sherlock Holmes thing. I found several older computers that were spewing noise via mouse and keyboard cables. Used ferrite blocks to cure that. Try listening to the noise while turning off stuff in the apartment. You'd be surprised what could be making noise.
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