The main problem that can cause export cropping issues is if you have the object on non-integer absolute coordinate or if the object has non-integer scale (with fractions). Absolute means all frames it’s nested in should be at integer coordinates too. Or you can align it to the absolute pixel grid ignoring underlying frames, but I think the former is simpler.
That’s because export works slightly differently than what is displayed in Figma. It’s a bit easier to explain with raster images but the similar logic applies to SVG export too. Let’s say you have a 10x10 image at 0.5 coordinate. Subpixels will be turned into full pixels and since the image starts on pixel 0 and ends on the 11th (10.5), it will be exported with width/height of 11 pixels. This obviously is not the case for SVG since it can take absolute values but I guess it calculates the bounding box this way. Maybe because SVG can contain raster images.