You’re clearly very defensive op. No one wants to fight with you. You asked a question and people are trying to answer gently but genuinely .
it is by far not the norm to be breastfeeding a child of this age, this doesn’t mean a small minority of people don’t do it and older, or that it’s not ok. It is.
People find it discomfiting because a child this age can usually talk, feed themselves, go to the loo themselves, dress themselves have a drink themselves, he will be going to school soon enough. Comfort at this age is more commonly hugs, cuddles, time together reading, talking, playing that sort of thing, not generally a breast in the mouth, which in western society is more associated with infants . It’s the same with dummies. It’s not about sexualisation but more about infantilisation. He doesn’t know any different, as an adult you make this decision. And the decision is ok,
rhe point remains, if you and your child still like this and want to do this, then it’s no one else’s business.