I installed the app on an old, cleared phone, got whatever app-only coupon they were offering at the time, turned that phone off and put it back in the drawer. Every other purchase I’ve made through the website and it’s been fine. I’ll admit to being hesitant to having the app in the background 24/7 on my daily “real” phone.
I did have a rare failure recently with a collapsible kitchen basin that leaked out the plug. When I went to return it, I included a gardening accessory that wouldn’t fit the tool (my fault but as long as I was filing a return anyway…) and Temu just refunded my money and said to keep them. Not that a leaky basin is any great score but at least I didn’t have to mess with boxing them and going to the shipping store.