https://www.snopes.com/fact-check/canned-pumpkin-isnt-actual...
[I'll just add one more note, not mentioned in the article, which is that typical Jack-o'-lantern pumpkins are quite awful for cooking. Much worse than any canned pumpkin. If you want to cook with fresh pumpkin, research the varietals that are known for good texture and flavor. Don't grab a carving pumpkin from the pile.]