Seems Affinity claims that the SVG output from Blender has the wrong encoding?
It looks like the file has an ascii encoding specified in it’s header but appears to be generated as utf-8 file. This I suspect is an error in the blender script. Other apps may be ignoring or using a different mechanism to obtain the encoding. If you’re doing a single image then it’s fairly straightforward to modify the svg file and replace the ‘ascii’ specification with ‘utf-8’ and then the file will load.