When I change a color to 2-color black and white, it's meant to add clean edge to the render (for easier tracing, etc), but 2019 does far worse than my X7 version. I've included the same picture, changed to B/W Lineart mode in both versions. You can see how X7 creates a crisp edge - while 2019 creates pixelated fuzziness around the edge.
Check our the rendering on the bird's head/beak below.
There are already methods that add textured edges if needed (ordered, halftone, Jarvis, etc) but Lineart should not be one of them. I'm not sure what was done in this upgrade to make things worse. Is there a setting in 2019 I'm missing that will make it work well like X7?
I understand that's very disturbing.
I think that is not a problem with how the conversion to black and white is being done, but rather, a difference in the way that CorelDRAW is rendering the content on the screen when the view mode is "Enhanced".
Here is another thread that might be related to this: Photo-Paint 2019 - Exporting TIF to Import into CorelDraw blurred.