You are right. Changing that character in Affinity Publisher fixed it in the export as well! Thanks a ton! An oversight on my side, since the file was originally made in AI, which I don't have any more. After importing it in Affinity Publisher and making a few fixes, I tried exporting. And first I thought everything was perfectly OK, until I began enlarging the image and saw it were rasterized... And then I began encountering the above error.
Anyway, @v_kyr thanks a ton!
PS: I know AI had a feature called minify or something, which would pretty much circumvent this problema, while also making svg files smaller (it would generate SVG code with minimal IDs, indents, lines, and white spaces). Would that be possible for Affinity as well? Or am I just missing something?