The article addresses that. Because the media doesn't report on Biden supporters, the public gets the impression that no one likes him much. I also think approval ratings are not contextualized well, because you rarely see how many people who disapprove of Biden's presidency are right-wing and how many are leftists.
From a personal perspective, while I was not a reluctant Biden voter (would have never voted for Trump), he was far from the top of my list in the 2020 primary. I think, considering the obstacles he's faced, Joe has been a much better president that I expected. That's in spite of Republicans ratfucking student loan relief and robust electoral reform.