Way back when the hockey stick was first published, when I believed in global warming, I (and others) noted that the Medieval Warm Period had been deleted.
When questioned on this, the Global Warming crowd did not say 'opps', instead they tried to deny the Medieval Warm Period ever really happened. They did this for years, in constantly changing ways. When one of their "There never really was a Medieval Warm Period" arguments was demolished, they'd alter their points.
To this day, it is that behavior on their part that makes me EXTREMELY skeptical of ANYTHING they say.
Even if I absolutely believed the Warmists were correct, I still group them as unethical truth twisters for the fast and loose way they play with any problematic data.
Case in point on Warmist behavior: Last time I mentioned this, I was told that the Warmist never tried to delete the Medieval Warm Period. The internet is a wonderful thing, it is not hard to find the old 1990s controversy. They did, and have yet to explain themselves.