It's the same shit that's flooding Amazon right now. It's just cheaper to buy directly from China. A lot of the electronics will likely reflect the lower price point (I got a pair of Lenovo earbuds which are decent for the $10 I paid and actually don't seem to be knockoffs, but they're not exactly high quality). Some electronics will likely be scams, and anything with memory should probably be quarantined and wiped so you don't accidentally install a keylogger onto your system.

Clothing will be sized oddly or contain errors as they're being pumped out by what are basically sweatshops at high volume.

I mean, it's really hard to be ethical about buying clothing at all at this point without doing a ton of research - even established clothing brands have been caught out using factories with sweatshop conditions. But at least those established brands are likely to have some quality control that prevents harmful chemicals from being used - not necessarily so with Temu, they're very reactive (will recall when pointed out to them but not proactively checking) so that's another avenue to consider.