Colossians 2:16–17: Sabbath, Sunday, and Judgment
Colossians 2:16–17 forbids anyone from judging believers over feast days, new moons, or a Sabbath day, since those observances were a shadow pointing to Christ. The text removes the courtroom from the calendar question without making any day either a sin or a law.
Colossians 2:16–17: Lent, Judgment, and Shadows
Colossians 2:16–17 forbids letting anyone judge you over food, drink, festivals, or Sabbaths, calling them a shadow whose substance is Christ. That is a different question from whether you have failed at a voluntary Lenten discipline.