While Tesco don't really appear to have done anything particularly wrong in this instance I can see it must be a bit galling for the woman who was selling them on Etsy:
Company run by black woman sells product= no one notices.
Company run by (presumably) white men sells product= everyone applauds.
Obviously it's a bit more complicated than that, with Tesco already being a massive, well known brand and the other company being fairly new and not widely known, but I can see why this plaster issue doesn't sit well.