Honestly, I've noticed odd colorations on mine and I'm getting odd tastes out of it. Yours and mine may be some sort of clone - boxes aren't hard to replicate. If you're concerned, you may want to look into a Vision Aurora Bottom Feeder - it's a slight ever bit more of a hassle to vape out of than a Protank (but you don't have to rebuild or anything) and instead of a tank, it uses a little plastic bottle that you can squeeze the
juice up into a dripping atty, which are disposable (but last a long time and are said to work 10x better than a head), or you can also use a Nova head I believe (the device comes with a tube adaptor to allow it to use heads as well as atomizers) and you can throw the little plastic bottle away whenever you feel it's old and get a new one for probably a couple bucks. Most of the non-disposable parts of the device never come in contact with juice. Much easier to clean.
The only catch is you have to slightly pinch the plastic bottle (which is the "tank") every 3-5 puffs (some say every 5-7), but this allows for more control over wicking, giving you a better performance as well. It's virtually a squeeze-bottle tank, but works in generally the same way a pyrex tank does, with just a little annoyance. But for me, it's all about what's safe and performs well. I hear great things about them. About $25.
The only thing I have to do research on is just how safe it truly is to use juice in the specific plastic bottle they use - I have seen extreme etching on plastic bottles used to store juice - and I don't want any corrostion or chemicals seeping into the juice!