Chlorine bleach is sodium hypochlorite
Kills viruses, bacteria, fungi
the first thing chlorine reacts with is the minerals in the water, therefore reducing its sanitisation capabilities. The next thing it reacts with is ammonia, creating different chloramines, which chloramine it creates depends on the pH of the water, for general tap water it creates dichloramine (see this page https://cleanclothnappies.com/ammonia/).
These cholramines can be dangerous, when released in large quantities, because the reaction is exothermic ie. energy releasing, and releases a gas, but only when you are mixing pure or high concentration ammonia, with bleach, which is why bleach labels and other cleaning agent labels say ‘don’t mix with blah blah’. This isn’t an issue for say your toilet, or your nappies, because the ammonia created from urine is really minimal (see that above page again).