Ah this is a case of wanting to knock someone down to build someone else up.
I would say Lamar got a pretty good pass honestly, and honestly I would say all of those teams had better weapons than the Chiefs. Just to demonstrate though if I told you a QB was MVP 4 years ago, but since then has not matched those numbers, has more turnovers, and has not been able to finish the past 2 seasons, I would assume you would say 7-9 range for a ranking is fair. That is where the lists in 2023 had him.
Now the reason Mahomes gets more leeway is because he has more accolades. He has 2 MVPs (at the time Lamar had the 1), 3 all pro selections, and, at the time, 2 Super Bowls. Basically there was a multi season sustained period of success you can point to and go “well we have all of this evidence that he is not a flash in the pan so something is wrong”.
To back up a little to demonstrate how Lamar got a lot of leeway, let’s look at Hurts. Hurts a fairly great season 2 years ago and had an amazing Super Bowl where he dueled Mahomes and after that the lists had him 2-4. Fast forward just one bad year, which to note was not as statistically bad as 2020-2022 for Lamar, and he is not in the top 10 on almost any of the lists. The big difference is that people saw the Eagles and went “with that OLine and those weapons you should be dominant if you are top 10 but you look completely mediocre.” whereas for Lamar it was “They really need to build a team around Lamar and keep him healthy”. It’s why 4 years after his breakout yearLamar was considered top 10 but only one year removed Hurts wasn’t.