I've had quite a few items from Temu and most has been OK, a small portion has been superb especially considering the cost and another small portion has been rubbish but they take it back or refund you without issues. A lot of the cheaper stuff on eBay and Amazon is essentially the same as Temu/AliExpress but more expensive. I can't imagine there being any form of guarantee once you're outside of the initial returns period and this would put me off buying a lead acid battery from anyone except a trusted bona fide retailer. The exception would be if it was for a fixer upper that I wasn't planning on keeping for long.
Now personally I think there's a case for a cheap Temu lithium battery maybe? Maybe not....

dunno.