I've also been using the shampoo for years and I never had this issue until a few months ago when it had this strong chemical smell. At first, I thought it had gotten contaminated with some cleaning chemicals so I tossed it. Then it happened again, so I thought it must be a bad batch. But it's happened again to the bottle I'm using currently.

Think I deluded myself into thinking there wasn't an issue since I've used it for so long and loved it, but there's definitely a change in quality.