The new thing they are pushing in water supplies are chloramides, which as I understand it as a non chemist, is Chlorine but less likely to brake down and also more potent.
Most filters on the market will not filter this out, and even some bottled water has is. Costco’s water does if I am remembering correctly.
There have been times when I’ve turned on the faucet and there’s a very strong chlorine odor.