Some data points: I bought a Decathlon folding bike (Fold 500; new, ~450€) a few months ago. Using it many times a week (probably more than it's intended).

No issues so far. Internet reviews (https://www.decathlon.fr/r/velo-pliant-fold-500/343354/undef...) are quite positive as well.

I've had other Decathlon bikes when I was a kid/teen, I don't recall any issue either.