Krita supports SVG 1.1 which seems to not support layers.
If you use Inkscape and create a multilayer image, then Save it as SVG 1.1, it warns you that some features will be lost and it will then group each layer’s objects and produce a single layer image with each original layer as a grouped set of objects.
If you save as ‘inkscape svg’ (whatever that is) then Inkscape will open that as a layered vector image but krita will open it a a grouped single layer image.
Inkscape uses special markers that may be particular to Inkscape but I’ve no idea how all that works and how it may be different from other applications.
If you import that into krita, it treats that as a group, not a layer.
If you want to create multi-layer .svg files then you need to use Inkscape or some similar application. You can export each .kra vector layer as .svg and then bring them into Inkscape in separate layers.
You could also edit the .kra output .svg files with an XML/text editor to manually create the layer structures according to the svg specification for layers, however they are done. That would be possible but tedious.