I did a literature search on this a week ago and the studies are conflicting. There are some that show a lower response rate (measured by antibody titer) to some vaccines. No data on the COVID19 one but this particular doctor thinks that blunting your immune response to a vaccine (by taking tylenol or NSAIDS) is a real thing and recommends against it.

There was a front page article about his opinion in the Philadelphia Inquirer last week. Google won't show it to me as I don't have a subscription, but feel free to look for it.

There is way to little evidence to say he is right or wrong. I would not worry too much about taking some tylenol after a vaccine at this point.