The #1 cause of inflation is government spending. Period. Full stop. This debt bubble began long ago, Trump did not help it (especially with the Covid hysteria), and Biden doubled down on government spending.
The #2 issue to blame is “energy” and I would agree with you that the Keystone pipeline was the biggest boat in that lake.
I still think my statement stands and, maybe, gov’t spending is second. As a percentage of GNP, gov’t spending hasn’t changed as dramatically as inflation. From 2013 to 2020, inflation was generally 2% or less, but gov’t spending was huge. However, the inflation rate after Biden killed the XL Pipeline increased 5x the previous year and has remained high ever since. (https://www.usinflationcalculator.com/inflation/current-inflation-rates/)
While gov’t spending contributes to inflation, the data suggest other forces are at work in the Biden Inflation and I think the pervasive effects of his decision on XL are still rippling through the economy.