I don't understand why someome capable of self hosting would use a "Canva alternative" instead of something normal like Inkscape/Figma/...

Canva is so bad. It's impossible to align stuff properly. Text rendering is awful. Official builtin templates have horrible kerning. It's genuinely one of the worst graphic editors I've used, and I'm not even remotely a professional designer. I don't want a "Canva alternative", I want a normal editor.