I'm sorry this has happened to you. Have you contacted Temu directly? Another option is to watermark your work before publishing it. There are a number of inexpensive sights that allow you to watermark your work. It's not cost effective for thieves to go through the trouble of removing watermarks and it establishes it as yours, provable in court. I use https://watermark.ws ↗️.
well, in China they never cared about western copyright, ehmm ... but in this case they are not even selling it, it is just an ad for the "Diamond Painting" scam 😏 but yeah, these motifs sell in thousands everywhere, you could do that legally or try to license it to a brand 😉 https://images.app.goo.gl/YLxnyuwfEMYj8MbA8 ↗️