[Image loses quality when I manually reduce its size]

Hello, I have an image of 1024x576 px which I want to resize to 768x366 px, so I created a document with the later dimensions and placed the large image, then, using the handle I manually resized the image so it would fit the artboard (because the ratio is not the same, some parts were not visible, but that's intended). After I resized the image I noticed the quality was terrible, the pixelation was very noticeable and made the result unusable almost, how can I modify the dimensions of this image without destroying the quality? Thanks for your help!

[White gaps in between the shapes composing a QR code]

Thank you! Why did blocking those shapes changed something? For the first suggestion, I do that when I have problems with other projects in which I have at most ten lines misbehaving, but for this one it would be to long, as I have to make many of these qr codes

[White gaps in between the shapes composing a QR code]

I made a new one, when applying to add to certain shapes the gap gets even larger

qr-code-2.afdesign

[White gaps in between the shapes composing a QR code]

I thought I aligned them correctly, there are some cases in which even if I realign them some shapes will add correctly, and other one will have even thicker lines.

I use qr code monkey for the qr codes

[White gaps in between the shapes composing a QR code]

qr code.afdesign

[White gaps in between the shapes composing a QR code]

They align perfectly. I added a second screenshot of other shapes that have a gap in between snapped shapes, even I applied a boolean add to all of them

[White gaps in between the shapes composing a QR code]

I did try applying boolean "add" to some shapes, but for some cases it makes it even worse, you can see in the attached image above the thicker white lines are those I use add on, the rest thin lines are like that since the beginning, even if I manually move individual shapes to make them snap correctly. The only way of changing this is to make the shapes overalp

[White gaps in between the shapes composing a QR code]

I created a QR code and downloaded the SVG version to edit it in Affinity Designer, even though the shapes that make the QR code are made to snap, there is a white gap that also shows on the exported version, this sometimes happens when snapping to shapes, but because the QR code is composed of many small shapes, it is much more noticeable.