I don't know what Windows is doing to supposedly give you a better picture, but you're getting everything this monitor is capable of.
Let's start with; at less than $150 for a 27" monitor, this is, bluntly, a dirt cheap piece of hardware. I could only find a view reviews on it, and no one is impressed.
It has only an HDMI connector, so it isn't even correct to call it a computer monitor. HDMI is first and foremost a TV signal connection. A monitor should have at least one DisplayPort connector. You're stretching out a 1920 x 1080 image to fill a 27" space. That's a recipe for blurry all on its own.
On top of that, Apple treats HDMI as what it's supposed to be, a TV connection. If you get an expensive enough monitor, then HDMI can still work at higher resolutions (which it or course can since 4K HDMI TVs are common). But a monitor this inexpensive is not going to be seen as capable of anything beyond 1920 x 1080. And, of course, that's the highest resolution the manufacturer themselves note as being the top end.
This monitor is in the same league as the junk HD TVs they sell very cheaply every Christmas season. These TVs are made specifically for Black Friday sales. As cheaply made as possible from the cheapest, crappiest components. And they last as long as you would expect. Two years, if you're lucky, before it konks out.
