Lossless not lossless or just applied scaling that I do not want?

[shotcut]

@bengalack

But I still have issues with color bleed or blending of colors, even in lossless export

That is due to chroma subsampling, which is common in YUV color spaces. I have explained that in much detail here before, which you can search for. You can avoid that by switching to a RGB color space but many players will not handle it. If you ultimately will share the video using a web service like YouTube it will do that too, and you will have no control over it.

Color on edges of text/masks/etc

I figured out that there are a few reasons why this occurs and is different than GIMP: colorspace conversion, chroma subsampling, and non-linear color processing. The reasons combine to worsen the result. Start with a test project consisting only of RGB sources and filters. Here is mine shotcut bug 21255.mlt (8.8 KB) Export it with preset FFV1 but in the Other tab change pix_fmt=bgr0 to export it as RGB. Use VLC to playback the result and export frames as PNG. Do not use Shotcut with Video Z…

Interpolating imported low res images/videos

You are not experiencing scaling interpolation directly but rather indirectly through sub-sampled chroma. Nearly all video uses sub-sampled chroma. If you use File > Export Frame… the image is coming from the player, and the player always uses sub-sampled chroma to reduce the data transfer over the PCI bus to a GPU or video card. Then, the sub-sampled chroma is up-sampled to make a RGB image. One way to remedy this is to use the Export panel with a preset from the alpha or stills category. Th…

UPDATE: You can make the lossless/H.264 preset export in RGB by choosing it and then Export > Advanced > Codec > Codec = libx264rgb.