It’s been a couple of years since I’ve bought Banggood cells. I believe they used to sell genuine cells. I have several 30Q flat-tops that seem authentic and perform well.
However, I don’t trust their button-top 30Q’s. I think whoever is supplying them, is not using good cells. Out of 9 cells, 3 have gone bad. They suddenly developed very high self-discharge (about 10% per day). I unwrapped them, and they do look like genuine Samsung cells. But, they’re obviously not a very good grade. It’s possible they were rejects from the Samsung factory, but got “repurposed” by a 3rd-party.
That was all a couple of years ago. It’s certainly possible they’re selling fakes now. I’ve only bought cells from Illumn since then, so I can’t be sure.
Whatever the case, there’s more than just fakes you have to watch out for. You have to watch out for used cells (very easy to do that when adding a button top), or low-grade cells (which you simply won’t know).