Summary: I tried some items from them. The quality and fit is really poor. They often smell of chemicals. They are excellent about returns, however. Overall, I would avoid.
Deeper discussion.
Beware the toxicity of cheap factory clothing. You can read about it here; it is certainly not limited to Shein. I would even lump a lot of the cheap-ish clothing found on Amazon in this category. A lot of it ships from cheap factories and is super cheaply made. (You can tell by the really odd business names and labels.)
https://goodonyou.eco/chemicals-in-fast-fashion/
NOW... I don't know how clothing dyes leach out lead, etc. I don't have any training or knowledge in that area. I mean, if the dye isn't bleeding when washed or worn, is the dye actually slowly leaching out heavy metals and toxic chemicals? It is a good question and an invitation to know more.
Further, Temu, Shein, and other similar companies date mine up to the gadzooks. This is just one article, you can find many more. https://www.dailymail.co.uk/ne.....hms-harves
I actually regret having once downloaded the Temu app to my phone. (I have already deleted it.) I have no way of knowing what information of mine was mined and sold by Temu. If their manufacturing practices are full of ethical issues, why would their data mining be any different?
NOW... as an opposing viewpoint...
so much of our clothing is manufactured overseas, and especially in China, how do we know any of it is considered safe? Beyond Okeo-tex certification, we really don't. However, I simply do not find it realistic to buy all of my clothing with very strict guidelines, i.e., always thrifted, always organic, always fair trade, etc. I cannot do it and still afford to feed my family.
Still, I have yet to buy a blouse from a mid-priced retailer that smells of chemicals like Temu clothing does. So, I do think paying more when possible is really worth it. I own three Amazon dresses that are not high quality, but are a step up from Shein/Temu. I wear them and love them, though I don't plan to purchase more, or make it a habit.
There's a lot of give and take unless one is extremely strict with their buying and shopping ethos.