The SVG description for a color glyph is a complete, integrated piece. No additional glyphs are required for the SVG description, which makes it beneficial for fonts that support a large number of characters. In comparison, in the COLR table, a color glyph required components that have separated glyph IDs.

Opentype-SVG usually has a larger file size compared to COLR and other color formats.

Opentype-SVG can't support variable glyph outlines. When making variable color fonts, Microsoft’s COLR/CPAL system is the only option right now, as the others are incompatible with the interpolation.

Being a complete integrated piece brings Opentype-SVG another drawback. Since the colors are ‘hard-coded’ into the font, there is no possibility to access them with css. Hopefully, this might change with the implementation of a COLR/ CPAL table.