Honestly, I don't know if anyone else feels the same, but I feel it's something that needs to be said, as I've seen your work many times in the past and it's not just a background that can make people not want to follow your work.
Your drawings look a lot like stock photos. Like someone has previously mentioned, they look more like diagrams than actual drawings. I don't know what drawing methods/techniques you use, but a lot of the times your drawings/compositions do come across as stiff and uneventful, even during the eventful scenes (which I know you do a fair bit of because of the genre of your comic being crime/drama/etc.) When you can't see any life being breathed into the characters, it can create a very "office" atmosphere (outside of actual office scenes lol). People want to read comics to be entertained, not to be brought back down to the drudgery of real life.
I want you to go and find examples of both manga and webcomics, specifically color ones. Take a look at colored works like Fisheye Placebo, Sanity Circus, Grassblades, etc. and see how they handle movement in their comics. Experiment with your panelling, don't feel like you're limited to a box. Use some different angles, take the time to adjust your scene to be more dynamic and interesting. Obtaining some kind of intense dynamic to your comic is important, especially when it's in comics that are more drama based and may get slow at times in plot. Don't just think about it in comic form either - what would it be like to watch this as a movie? How would the camera angles be placed? Where would you place your actors? If you couldn't imagine watching it on the big screen, chances are it won't work very well in a comic (this is just a general rule of thumb though; comics have the extra advantage of being able to cut panels and break out of them and such). I know if I was watching this specific example play out on screen, it would come across as very poor, as there's a lot of negative space surrounding the characters (and not in a good way) the colors don't stand out, and the composition is just not very structured.
And no, you don't need to shade in comics, but doing flat colors along with just flat environments in essence makes the entire scene come across as boring and dull. So yes, I'd suggest you learn how to shade and render lighting as well because it's definitely a viable skill to have and can add so much more depth to your work - but remember that the composition as a whole, from layout to BG to expressions, etc. will be what will really make your comic pop.
Sorry if a lot of this comes across as harsh, I've seriously been meaning to give you a critique like this for a long time and this seemed like the best opportunity to xD You could have a very dramatic, intense comic to read here, but its visual setbacks are keeping it from obtaining that depth. Even if you need to take the extra time to redraw a scene or set up the background or experiment with expressions, whatever - this is comics, and in 2D work, exaggeration and clarity is everything. Don't settle for mediocre.
Specifically speaking backgrounds though, I like the first one better just because it has a bit more to it. However drawing your backgrounds would be a good replacement if you were willing to put in the amount of shading and detail that the first version has to recreate the depth in the room.
